Both a family history of alcoholism (FH+) and a personal history of Antisocial Personality Disorder (ASP) increase the risk for developing alcoholism, particularly among males. Previous studies suggest that a reduced P300 event-related potential (ERP) amplitude is a marker of the presence of a family history of alcoholism. The present study examined the effects of both a FH+ and a personal history of ASP in relation to the P300 amplitude in a sample of 79 nonalcoholic young men. Reduced P300 ERP amplitudes elicited by a visual oddball task were found at the frontal electrode sites for both the FH+ and ASP groups, but not their interaction. There were no group differences in P300 latencies. P300 amplitude at Pz was associated with behavioral measures of figural memory, while P300 at F8 was associated with behavioral measures of cognitive flexibility.