College students hypothesized as being at risk for psychiatric dysfunction solely on the basis of their MAO platelet activities were briefly interviewed 2 years after completion of initial studies. These 33 low-MAO subjects reported more job instability than 30 high-MAO control subjects. Moreover, the low-MAO males had fallen about half a year behind their high-MAO counterparts in school. No differences in other aspects of social status or psychosocial problems had developed, although the low-MAO subjects smoked significantly more cigarettes and tended to report more major or minor medical problems. While the low-MAO subjects reported no significant decline in their own mental health status during this period, more low-MAO male subjects did report mental health problems in their families, especially depression, alcoholism, and suicide attempts, as well as significantly more mental health interventions among family members, such as psychiatric visits, prescription of psy-chotropic medication, and psychiatric hospitalization.