We have presented a case of an osteochondroma involving the transverse process of L3 in a 17-year-old man with no evidence of other osteochondromatous lesions. The growth of the lesion was extremely rapid but demonstrated benign histology. This patient was asymptomatic and had a normal physical examination despite the size of the lesion. The benign scoliosis in our patient appears to have been unrelated to and unaffected by the osteochondroma. Whether the osteochondroma would have reached sufficient size to cause significant visceral or neurologic compression, such as in the case presented by Gokay and Bucy, if he had not been treated for scoliosis is a matter of conjecture.