Griseofulvin is a polyketide synthase-derived fungal metabolite originally isolated from P. griseofulvum with antifungal and anticancer activities.^1,2 It inhibits microtubule assembly when used at concentrations ranging from 20 to 200 µM.³ Griseofulvin is active against a variety of dermatophytes (MICs = 0.14-0.42 µg/ml) and reduces the number of infected hair follicles in a guinea pig model of M. canis infection when administered at a dose of 60 mg/kg.^4,5 It also reduces viability of a variety of human colorectal cancer cells in vitro and induces abnormal mitotic spindle formation and cell cycle arrest at the G2/M phase in HT-29 cells when used at a concentration of 20 µM.⁶ Griseofulvin (50 mg/kg) reduces tumor growth in a COLO 205 mouse xenograft model. Formulations containing griseofulvin have been used in the treatment of dermatophyte infections of the skin and nails.