The aim of this study is to evaluate the degree of familial aggregation of type 2 diabetes mellitus in Morocco and to investigate transmission patterns of the disease and their relationships with patients' clinical profiles. Family history of diabetes and clinical data were collected from 232 unrelated type 2 diabetic Moroccan patients. Diabetes status was recorded for first degree (parents, siblings) and second degree relatives (aunts and uncles from both maternal and paternal sides). Among studied subjects, 50% reported at least one relative with diabetes and 24% had at least one parent with diabetes. Familial aggregation of type 2 diabetes was prominent and more important among first degree relatives than second degree relatives (P < 0.01). Moreover, diabetes was more frequent among mothers than fathers of probands (P = 0.02), but this maternal effect was not observed in second degree relatives. There are no significant differences in clinical and metabolic profiles between patients according to the transmission pattern of the disease. In conclusion, these results suggest familial aggregation and excess maternal transmission of type 2 diabetes in the Moroccan studied population.