The prevalence of sensorineural hearing loss, measured by pure tone audiometry, was determined in 66 patients with chronic renal failure and threshold changes following haemodialysis were measured in 31 patients. The incidence of hearing loss was 41% in the low, 15% in the middle and 53% in the high frequency ranges respectively. No correlations with weight changes, haematocrit, metabolic bone disease or ototoxic drug history were found. Of 62 ears studied, 38% had a decrease in low frequency threshold after dialysis and 9% had an increase. Threshold in 22/31 ears with pre-existing low frequency loss altered after dialysis with little change in other frequencies and no correlation with weight changes. In conclusion, we find a high incidence of low and high frequency hearing losses in chronic renal failure patients. Fluctuation in low frequencies with dialysis is common. Possible mechanisms include treatment induced changes in fluid and electrolyte composition of endolymph.