Ten women with recurrent vulvovaginal candidiasis (RVVC) due to Candida albicans were followed for a mean of 35.3 months, and 81 vaginal isolates were evaluated by pulsed-field gel electrophoresis for strain delineation. The initial strain of C. albicans isolated was unique to each patient; in addition, in 8 women, only 1 strain type of C. albicans was identified throughout follow-up. In 1 patient, 3 strains of C. albicans were identified over a 27-month period and in another, 2 strains were recovered over a 30-month period. Two pairs of women shared identical strains of C. albicans. These results confirm the enormous diversity of strain types of C. albicans and demonstrate the persistence of colonization with the same strain over prolonged periods despite therapy. Results also support the concept of recurrent vaginitis being due to vaginal relapse or endogenous reinfection with the identical strain.