Previous studies have examined the role of genetic variations in the serotonin transporter-linked polymorphic region (5HTTLPR) in affective disorders. The authors studied 182 older depressed subjects and 107 elderly control subjects and obtained DNA for genotyping at the 5HTTLPR. There were no significant differences in allele frequencies generally or for number of short alleles for the group as a whole, but interesting gender effects emerged. Among men, 23% of depressed men had two short alleles, compared with only 5% of control subjects. Among women, 67% of depressed women with more than one episode had at least one short allele, compared with 41% of single-episode female patients. Also, 74% of women with a positive family history of psychiatric illness in any female relative had at least one short allele, whereas 53% had at least one short allele who did not have such a family history. Our results add to the literature linking this gene to affective illness. The negative association of allele frequency and depression may be related to the relatively small sample size. The findings raise the possibility that this genetic locus may exert differential effects based on gender, increasing risk in men, and increasing risk of recurrence in women.