The scanning electron microscopic pattern of the development of yeasts of Candida albicans on the vaginal mucosa of mice in oestral phase, was studied in four consecutive infections performed at 30 d intervals. The findings were practically identical following the 1st and 2nd infections, evidencing a progressive mycelial development starting from 12 to 72 h after inoculation with C. albicans yeasts. In the 3rd and 4th infections the mycelial tufts appeared extremely reduced in number and size, although there was an acceleration in the early evolutive phases and the filamentation process had already started 6 h after infection. It can be concluded that, after successive infections with C. albicans, mouse vaginal mucous membrane develops a local state of resistance evidenced by the decrease in mycelial tufts. The possible causes of the early onset of the filamentation process are discussed.