Cat scratch disease is a rare infectious disease caused by the Gram-negative bacterium Bartonella henselae. Most often, it affects children and adolescents. Infection occurs primarily through bites or scratches by a cat, or less commonly a dog, rabbit or guinea pig. It is transmitted also by body lice and cat fleas. It most often occurs in the form of local lymphadenopathy, in individual cases there may be symptoms of generalised disease. The paper presents a case report of an early diagnosed and confirmed by serological tests cat scratch disease in an 8-year-old boy. The symptoms in the form of painful inguinal lymphadenopathy were observed 3 weeks after the boy sustained a cat scratch in the navel area. Except for a slightly accelerated erythrocyte sedimentation rate, the laboratory findings were normal. After 10-day hospitalisation, improvement of the patient’s overall condition and a significant reduction in lymph nodes size were achieved, and the pain was eliminated. Cat scratch disease is correctly diagnosed increasingly often, yet it still frequently poses a diagnostic problem.