Anxiety disorders are frequently observed in patients with breast cancer, they are often underestimated and in most cases undetected by attending healthcare practitioners. This can negatively affect treatment outcomes and quality of life in patients with breast cancer. This study assessed the prevalence, socio-demographic and clinical correlates of anxiety disorders in patients with breast cancer. It also determined the quality of life in these subjects. The subjects were made up of 200 female patients with breast cancer attending the Oncology Outpatient Clinics at Lagos State University Teaching Hospital (LASUTH).They were selected by systematic random sampling, having consented and met the inclusion criteria of the study. The participants were assessed with a Socio-demographic and clinical profile questionnaire, Hospital Anxiety and Depression Scale, the Schedule for Clinical Assessment for Neuropsychiatry, European Organization on Research and Treatment of Cancer Quality of Life Questionnaire(EORTC-QLQ-C30) and its Breast specific quality of life questionnaire (EORTC-BR-23). The data obtained were analysed using SPSS 16. The mean age of the subjects was 49.6+11.2years. The majority were married (76.5%), had completed secondary education (61%), employed (69.5%), and were from monogamous family setting (76%). A larger proportion of subjects derived their major source of support from relatives (66.5%). The mean duration of illness was 8.79 + 5.08 months. More than half of the subjects (55%) presented with the advanced form of breast cancer. The commonest mode of treatment was chemotherapy. The prevalence of Anxiety disorders in these subjects was 23.5% determined by weighting method. .The largest proportion of subjects with anxiety disorders had mixed anxiety and depressive disorders (44.7%). Anxiety disorder was found to be significantly associated with marital status income (p=0.029), staging of breast cancer (p=0.018) and previous history of breast cancer (p=0.004). Stage of cancer and previous history of breast cancer were predictive of anxiety disorder in patients on binomial logistic regression. On the EORTC QLQ C-30 the results of, the mean global health score (61.04%) and the five functional scales (64.42-79.08%) indicated that the participants had above average functioning while 8.50%-48.50% met the criterion for more severe symptoms For the Breast Cancer Specific QOL Questionnaire, 18.40%-71.10% of the participants met the >66.7 criterion for good functioning on the functional scale while only 7.50%-24.40% of the participants had severe symptoms on the symptoms scale. Subjects with anxiety had statistically significant lower mean scores on the global health status domain and in the functional domain of EORTC-30 than those without. On the symptom domain, the mean scores of the participants with anxiety disorders were higher (denoting poor functioning) and this was noted to be statistically significant in all the domains with the exception of constipation, dyspnoea and nausea with vomiting. Subjects with anxiety disorder had statistically significant lower mean scores in the entire functional domain of the EORTC-QLQ-C30). On the symptom scales, subjects with anxiety disorder had higher scores (denoting poor functioning) than those without with an exception being in the arm symptoms. The results indicate that Anxiety disorders is significantly associated with a lower quality of life in patients with breast cancer . Sociodemographic factors were noted not to have a significant association with the development of anxiety disorders in breast cancer patients (with the exceptio