Introduction: Trichomycosis is a superficial infection caused by Corynebacterium flavescens, which regularly affects axillary, and to a lesser extent, pubic, scrotal and intergluteal, and exceptionally, head hairs or trichomycosis capitis (TC). This condition is characterized by the formation of bacterial nodules. Clinically, it can be confused with white stone or pediculosis. The diagnosis is made by microscopic and dermoscopic observation, and confirmed by culture. Objective: To present a case of TC in an infant, with emphasis in the microscopic, dermoscopic, and ultrastructural characteristics. Clinical case: A 6 month-old boy, otherwise healthy, with multiple yellowish concretions on the hairs of the head. TC was confirmed by yellow fluorescence with Wood's light; white-yellowish beads, like "rosaries of crystalline stones'' were observed on dermoscopy, direct examination showed bacterial masses, and Corynebacterium flavescens was identified by culture. A superficial infection, without perforation of the hairs, was confirmed by electron microscopy. Treatment with fusidic acid for 3 weeks achieved a clinical and microbiological improvement. Conclusion: TC is a rare condition that affects children, and tends to be mistaken with other diseases of the hair, such as pediculosis and mycotic infections.