Three hundred twenty-four cases of scalp ringworm among Negro school children were studied in Miami, Fla. Approximately one half of these were nonfluorescent infections due to Trichophyton tonsurans, the remainder being fluorescent Microsporum infections, of which one in every four cases was due to M rivalieri, a newly described African species closely related to M audouinii. In the T tonsurans infections, neither a single 3-gm dose of microcrystalline griseofulvin nor four 1-gm doses at weekly intervals was considered effective therapy. Daily doses of griseofulvin are recommended for the treatment of nonfluorescent tinea capitis. In contrast, a single 3-gm dose plus a topically applied benzoic and salicylic acid (Whitfield's) ointment was curative in 88% of the Microsporum infections. Attention is again drawn to the increasing incidence of nonfluorescent Trichophyton infections of the scalp in the United States.