A prospective study of auditory function in 18 HIV positive male patients at different CDC (Centres for Disease Control) stages was undertaken. One-third had abnormalities on either auditory evoked response testing or pure tone audiometry. No correlation was found between interwave latencies I-V, I-III, III-V and stage of disease determined either clinically or by T-cell subset. There was a weak correlation between pure tone averages at 1,2,4 kHz and 2,4,8 kHz and T-cell subset ratio in CDC Group IV disease (Rs = 0.56 and 0.57 respectively; P less than 0.05). Abnormalities of BSER were similar to those previously reported in HIV infection, and suggest isolated changes within the brain-stem.