Recurrent subacute torsion: prospective study of effects on testicular morphology and function. A prospective study was done on 43 consecutive patients with a diagnosis of recurrent subacute testicular torsion. All patients underwent full examination, hormonal assays and seminal fluid analysis before scrotal exploration, bilateral testicular biopsy and fixation. Seminal fluid analysis and hormonal assays were repeated 3 months postoperatively. Of the patients 36 were cured of recurrent pain, 35 of whom had a horizontally lying testis. No hormonal abnormalities were found preoperatively or postoperatively. Three patients had abnormal seminal fluid analysis. Testicular biopsies, including Johnsen scores, were abnormal in these 3 patients and normal in the other 33. It is concluded that patients with recurrent subacute torsion can be identified accurately and treated satisfactorily. There is little evidence that these patients suffer testicular damage as a result of this subacute torsion or that any pre-existing cellular abnormality exists to explain the oligospermia that frequently is seen in patients who have acute testicular torsion. 