To monitor the relative prevalence and evolutionary trends of HIV-1 in Uganda, we conducted a retrospective study of pregnant women over the time period 1989-2000. From a total of 300 women sampled, we defined subtypes by heteroduplex mobility assay for 230 subjects and by partial sequencing and phylogenetic analyses of the env gene for 216 subjects. Subtypes A and D were most prevalent, and there were no significant trends in relative frequencies of subtypes A (45%), D (41%), C (5%), or recombinants (9%) over the 11 years sampled. There was also no phylogenetic clustering of subtypes related to geography (clinic location) or year of collection. Mean pairwise nucleotide diversity of subtype A (pi = 0.163) and subtype D (pi =0.156) samples did not differ significantly between subtypes, nor did these levels change over the period of the study. This report suggests that among pregnant women in Uganda A and D subtypes are transmitted without geographic constraints, and are not associated with significantly different transmission rates.