An 8-year-old boy was admitted to hospital with acute testicular pain. A diagnosis of torsion of the testicle was made, and an orchidectomy was performed. Histopathological study showed necrosis of the testicular parenchyma caused by arterial obstruction, and adults of Angiostrongylus costaricensis were found within the spermatic arteries. In addition, heavy eosinophilic inflammatory reactions and unfertilized eggs were observed in the excised tissues.