A 6-year-old Haflinger gelding was presented with a chronic right hindlimb lameness. Scintigraphy, radiography and computed tomography confirmed an active large cyst-like lesion in the distal metaphysis of the right tibia. A transcortical surgical approach was used to curette the lesion and fill it with an autologous bone graft and a calcium phosphate bone substitute material. Histopathology revealed mild histiocytic inflammatory changes, mild fibrosis and bone necrosis. This case report describes an unusual cyst-like lesion in the tibial metaphysis of a horse.