Joint psychiatric admission to a Mother-Baby Unit (MBU) enables a mother to obtain care for psychiatric disorders and simultaneously receive support in developing her identity as a mother. This care is meant to prevent attachment disorders and mother-baby separation. Outcome at discharge, however, may differ according to the mother's admission diagnosis. Demographic data, clinical features of parent and child, and clinical outcome of 92 consecutive admissions of mothers and their children to a MBU in Marseille were collected over a period of eight years (1991-1998). Separations occurred in 23% of the joint admissions. Women with acute postpartum psychoses and major depressive disorders had better outcomes than those with chronic psychoses: at discharge, the latter were more often separated from their children. In those cases, however, MBU admission provided time to arrange the best placement for the child. Outcome was less predictable for non-psychotic personality disorders and depended not only on the mother's disease but also on her family and social context.