7-Chloro-3-[1-(2,4-dichlorophenyl)-2-(1H-imidazol-1-yl) ethoxy-methyl] benzo [b] thiophene (sertaconazole, FI-7045, CAS 99592-32-2), a new topical antifungal agent, has shown activity against a broad range of clinically relevant yeasts and fungi. In the present study, the molecular basis of the pharmacological action of sertaconazole was examined by investigating the inhibition of ergosterol synthesis in cultures of Candida albicans, ATCC E-10.231, at 6 x 10(5) cells/ml grown aerobically at 37 degrees C, using various concentrations of sertaconazole. Sertaconazole inhibited the ergosterol synthesis with IC50 = 115 nmol/l. The results show that one of the mechanisms of action of sertaconazole consists in the inhibition of ergosterol synthesis.