Brucellosis is an important public health problem in Turkey as well as in the world. The disease manifests with non-specific symptoms such as fever, joint aches, and sweating, and doxycycline has an important place in its treatment. Doxycycline is a broad-spectrum tetracycline antibiotic used in the treatment and prophylaxis of various inflammatory and infectious disorders. Along with several systemic complications (i.e. esophagitis, hepatotoxicity, diarrhea), doxycycline is also known to have phototoxic effects. Photoonycolysis, rarely accompanying phototoxic reactions, is the detachment of the nail plaque from the nail bed with exposure to ultraviolet light. The aim of the current case report was to present a patient, who was placed on doxycycline therapy due to brucellosis and who developed photoonycolysis in all fingers of the hands.