It is common practice to diagnose spondylolysis with oblique radiographsof the lumbar spine although antero-posterior and lateral radiographs aretaken routinely for patients with lower back pain. The author has acquiredmore understanding about the radiographic features in the antero-posteriorand lateral views through a study of radiographs taken from artificial imi-tative specimens of spondylolysis. Eleven typical features have been identi-fied and with their aid the plain radiographs of 169 cases of spondylolysishave been analyzed. The results have been compared with those obtainedfrom oblique views. The percentage of diagnoses achieved by plane filmshas been determined at 89.1% with the antero-posterior view, 81.6% with thelateral view and 93.1% with the oblique views. If spondylolysis can bediagnosed with antero-posterior and lateral radiographs alone, the diagnosiswill be more expeditious and economical.