INTRODUCTION: Self-stigma of mental illness is a cognitive and emotional phenomenon experienced by some patients. It happens when a person internalizes negative public views about himself/herself. Self stigma can restrict access to mental health care, it delays treatment seeking, hinders recovery and leads to poor quality of life. There is dearth of research on self-stigma of mental illness among people with schizophrenia and HIV/AIDS. AIMS AND OBJECTIVES: The study compared self-stigma of mental illness among patients with schizophrenia (females and males) and among female patients with (schizophrenia and HIV/AIDS) attending clinics at two hospitals in Maiduguri: Federal Neuropsychiatric Hospital and University of Maiduguri Teaching, respectively. It assessed (1) the relationship between self stigma, socio-demographic and clinical variable of the respondents and (2) the relationship between being a parent and self stigma of mental illness among female patients with schizophrenia. METHODOLOGY: The study consisted of a study group (females with schizophrenia) and two comparative groups (males with schizophrenia [comparison A] and females with HIV/AIDs [comparison B]). It was a cross sectional, hospital-based survey that recruited a total of 450 participants and 428 completed the study. Instruments used for the survey included: (1) Socio-demographic Questionnaire, (2), Modified version of the Internalized Stigma of Mental Illness (ISMI) Scale (3) Brief Psychiatric Rating Scale (BPRS), (4) Morisky 8 Item Questionnaire assessed medication adherence (5) Oslo 3 Social Support Scale, (6) Simpsons And Angus Scale and (7) Recovery Attitude Questionnaire. Analysis was done using Statistical Package for Social Sciences (SPSS), version 18. RESULTS: The rates of self stigma of mental illness among males with schizophrenia, females with schizophrenia and females with HIV/AIDs were 70.2%, 68.3% and 61% respectively. The correlates of self stigma of mental illness differed among the three groups of patients. Among females with schizophrenia (study group), high self stigma was associated with parental status of being a parent (χ2 =5.327, p= 0.021), being a Muslim (χ2 =7.375; p= 0.007), number of relapse of less than two (χ2 =7.259, p= 0.007) and normal/minimal BPRS score (χ2 =7.136, p= 0.049). But, among males with schizophrenia (comparison group A), high self stigma was associated with marital status of being married (χ2 =10.879, p= 0.028), Qur’anic education (χ2 =14.198, p=0.007) and high medication adherence (χ2 = 6.594, p=0.037). Furthermore, among females with HIV/AIDs (comparison group B) high self stigma was associated with negative recovery attitude (χ2 =9.503, p= 0.002). Female patients with schizophrenia had a higher mean ISMI score compared to female patients with HIV/AIDs (2.59 ± 0.25 vs. 2.53 ± 0.28). There was a statistically significant total mean difference in self stigma of mental illness among female patients with schizophrenia and HIV/AIDs (t=2.13, p=0.034) but a statistically insignificant mean difference of self stigma of mental illness was observed between females and males with schizophrenia (t=1.23, p=0.220). Females with schizophrenia that were parents had a higher mean score of self stigma (M 2.63 ± SD 0.26) compared with females with schizophrenia that were not parents (M 2.55 ± SD 0.22). Among female patients (schizophrenia and HIV) the highest mean score of self stigma was obtained on discrimination subscale (M 2.79 vs. M 2.82) while among male patients with schizophrenia the highest score was obtained on the stereotype experience subscale (M 2.69). CONCLUSION: Self stigma of mental illness is pervasive; it is seen among patients with schizophrenia and HIV/AIDs. However, it is more prevalent among patients with schizophrenia. There is the need for stigma reduction interventions as well as creation of advocacy groups to reduce self stigma of mental illness among these patients and to improve their quality of life