Miconazole tested in vitro against the most important fungi pathogenic for man and animals, and against gram-positive bacteria has proved to be highly potent. The dermatophytes, yeasts, dimorphic fungi, Aspergilli and the mycetoma-causing agents are the most sensitive. This activity was confirmed by in vivo tests on guinea pigs infected with Trichophyton mentagrophytes, Microsporum canis or Candida albicans. Miconazole used orally or topically was very active against experimental tinea and candidosis in guinea pigs. For each test, the authors compared the activity of miconazole with different reference compounds.