At our hospital, we recently began to manufacture antifungal creams containing 40% urea to be dispensed to onychomycosis patients who either had griseofulvin-resistant onychomycosis or who could not tolerate griseofulvin treatment for systemic disease. We utilized six commercially available O/W type antifungal creams to manufacture the preparations. By noting whether these preparations could be stocked as intramural preparations and using various methods, we discovered that we could generate the surface active agent in these preparations by adding calcium oxide and oleic acid. The creams prepared using this method were then manufactured under aseptic conditions and stored either at 5°C, room temperature or 40°C for 4 weeks to investigate the base stability of the preparations. Based on naked eye inspections and microscopic examinations of the visual changes with the passage of time, we investigated whether or not the emulsion in these preparations was destroyed. The quantity of the water phase separated by centrifugation, which was employed as an indicator of the destruction of the emulsion, was then measured. We thus found that the base of these preparations remained stable for 4 weeks at room temperature