In developing countries, families play a major role in caring for the mentally ill and in many instances they are the first to provide the primary care and support needed by patients. Previous studies assessed the level of family support by the number of family members patients had contact with regularly; or the number of the various types of limited tangible aids patients receive from their families. The degree to which the patients perceived how their needs for support were fulfilled by their families was minimally assessed. This study is a step further in assessing to a larger extent, the level of perceived family support and the socio-demographic/clinical variables that are involved in its relationship to the quality of life of patients with schizophrenia and major affective disorders. It was a cross-sectional study of 137 patients with schizophrenia and 268 patients with major affective disorders attending the outpatient clinic of Federal Neuropsychiatric Hospital Kware Sokoto, for follow-up care. Diagnoses were based on ICD-10 Diagnostic criteria for research. The questionnaires administered to the participants consisted of a proforma to elicit socio-demographic/clinical factors, self-rated 26-item World Health Organization Quality of Life-BREF assessment instrument (WHOQOL-BREF) and self-rated 20-item Perceived Social Support-family scale (PSS-Fa). Data was analysed with the 13th version of the Statistical Package for Social Sciences. Those with good family support where 92.1% among patients with schizophrenia and 82.1% among those with affective disorders. However, patients with affective disorders were significantly more associated with higher scores of family support. (T=2.09, p=0.04). Poor family support was significantly more associated with poor overall QOL, poor overall health and poor social domain QOL than good family support among patients with schizophrenia. While among patients with affective disorders, poor family support was significantly more associated with poor overall QOL, poor psychological domain QOL and poor environmental domain QOL, than good family support. These associations remained after controlling for possible confounding factors using logistic regression analysis. Among patients with schizophrenia, good family support was significantly more associated with receiving financial aid from the family (OR=8.32), advice from the family (OR=23.60) and visits from the family (OR=5.75) than poor family support. While for patients with affective disorders, good family support was significantly more associated with receiving advice from the family (OR=6.24), visits from the family (OR=4.37) and clothing from the family (OR=2.38) than poor family support. Poor family support was significantly more associated with longer duration of illness, longer duration of treatment and almost reached significance with older age than good family support among patients with schizophrenia. It is therefore important to assess the level of perceived family support regularly and to identify the possible factors which may make family support inadequate among patients with major mental disorders. These will assist mental health professionals in conceptualizing patients’ problems in a more comprehensive manner and also strengthen the family support system necessary for optimum quality of life of patients.