BACKGROUND Depression is the leading cause of disability as measured by years lived with disability (YLDs) and the 4th leading contributor to the global burden of disease (DALYs – disability adjusted life years) in 2000. The consequences of major depressive disorder extend far beyond the affected individual and are borne by close family members and friends as well as the community. Although carers and families of people with mental disorders are a crucial part of health and community support systems, their experiences are rarely explored systematically. Hypertension on the other hand is regarded as a major public health problem and an important threat to the health of adults in sub-Saharan Africa. Emerging evidence identifies hypertension as a major cause of morbidity and mortality globally including sub-Saharan Africa. There is dearth of published research on caregiver burden occurring in the context of depressive illness and hypertension in Nigeria. Thus, research in this field is essential. OBJECTIVE The objective of this study was to assess caregiver burden among relatives of patients on treatment for depressive disorder and compare it with the caregiver burden in relatives of patients receiving treatment for hypertension attending the outpatient clinics (psychiatry and cardiology outpatient clinics) of the Obafemi Awolowo University Teaching Hospitals Complex (OAUTHC), Ile Ife, Nigeria. METHODS A total of two hundred subjects were recruited of which one hundred were caregivers of patients with depression and the other hundred caregivers of hypertensive patients. They were matched for age and sex. The caregivers of patients with ICD-10 diagnosis of depressive illness who had been on outpatient treatment for at least six months were consecutively recruited from the psychiatric outpatient clinic of the OAUTHC. Caregivers of hypertensive patients were also recruited from the cardiology clinic of the OAUTHC. The hypertensive patients were diagnosed by a Consultant Cardiologist and had also been on outpatient treatment for at least six months. The caregivers of the depressed and the hypertensive patients completed a semi-structured socio-demographic questionnaire, the Zarit Burden Interview and the General Health Questionnaire (GHQ 12). The Statistical Package for Social Sciences (SPSS) software (version 11) was used for analysis. RESULTS The mean ages of the caregivers of the depressed patients and the hypertensive patients were 46.23 years and 46.17 years respectively. In the two groups, 65.0% of the respondents were males while 35.0% were females with majority being within the age range 35 – 44 years (41.0%). Ninety five percent (95%) of the caregivers of patients with depression and 99.0% of caregivers of hypertensive patients were married. Christians were in the majority with 73.0% and 76.0% of the caregivers of the patients with depression and the caregivers of the hypertensive patients respectively being Christians. Also, 93.0% of the relatives of the patients with depression belonged to the Yoruba ethnic group while 99.0% of the relatives of hypertensive patients belonged to this ethnic group. The caregivers of the hypertensive patients were better educated as they had more Secondary and University education. All the respondents in both groups were employed with the average monthly income of the carers of the depressive disorder patients being 39,220 Naira while carers of the hypertensive patient earn 59,940 Naira monthly on the average. The difference in income was statistical significant (t=3.027, p= 0.003). In the majority of the care giving situations, the spouses were the caregivers with 57% of the carers of the depressed patients being their spouses while 46% of the caregivers of the hypertensive patients were their spouses. The mean ages of onset of the depressive illness and of hypertension were 37.45 years and 54.51 years respectively. This difference was statistically significant (t=11.39, p<0.001). The depressed patients had a mean duration of illness of 52.08 months while the mean duration of hypertension was 62 months (difference not statistically significant t=1.89, p= 0.06). There was a statistically significant difference in the mean ZBI score of caregivers of patients with depression (41.32, SD = 9.82) when compared with the mean ZBI score of caregivers of patients with hypertension (32.12, SD=5.39, t = 8.21, p<0.001). Using the GHQ 12, among caregivers of the patients with depression, 21% were identified as cases while only one (1%) of the caregivers of the hypertensive patients was picked by the GHQ-12 as a case, this difference in finding was statistically significant (χ2 = 18.43, p < 0.001). The ZBI score correlated significantly with the age of onset of illness (r= -0.263, p<0.001) and cost of transportation (r= -0.20, p<0.05) among the carers of the patients with depression. Linear regression analysis showed that the age at onset of illness, cost of transportation and duration of care independently predicted ZBI scores among caregivers of patients with depression. CONCLUSIONS The caregivers of patients with depressive illness had more severe burden of care compared with the caregivers of the patients with hypertension. The burden of care was related to the age of onset of the depressive illness, the cost of transportation and to some extent the duration of care for the patients. The findings of this study suggest that care of the carers should be an integral part of management for patients with depression. Additional research will be necessary to elucidate further the factors that contribute to the burden of care in patients with depression and hypertension using larger samples of patient with a broader range of symptom severity