We studied the changes produced in Candida albicans yeast cells after treatment in vitro with sertaconazole, with light microscopy, transmission and scanning electron microscopy. Four different concentrations were evaluated (10(-6) M, 10(-5) M, 10(-4) M, 10(-3) M) and two times of action (12 and 17 h) for each concentration. This new antimycotic agent shows a considerable destructive effect in C. albicans cells. The alterations produced by sertaconazole were already manifested after 12 h at the concentration of 10(-6) M and a strong fungicidal activity recorded at 10(-4) M.