A spontaneous, cerulenin-resistant mutant of Candida albicans (strain 4918-10) was found to adhere less readily to human vaginal mucosal cells in vitro than a wild type C. albicans (strain 4918). In a murine model of vaginal infection, strain 4918-10 was found to be less virulent than wild type C. albicans, i.e., the infection rate caused by 4918-10 was only 31% of that observed with wild type, 4918. A chitin-soluble extract (CSE) prepared from 4918 blocked attachment of yeast cells to human vaginal epithelial cells, while CSE from 4918-10 did not significantly reduce the attachment of yeasts to vaginal cells. Both 4918 and 4918-10 produced hyphae in vitro and in vivo, were negative for proteinase production and grew equally well at 28 degrees C and 37 degrees C. The data suggest that adherence to vaginal mucosa may be an important determinant in the pathogenesis of vaginal infection caused by C. albicans.