Urate deposits within microtophi were found in 8% of unselected autopsies in Brisbane, Australia. Significant associations were demonstrated with (a) a history of gouty arthritis and (b) the existence of nitrogen retention and renal disease of apparently primary, but not gouty, origin. However, in 26% of the patients, a retrospective survey of their medical records did not reveal any causative factor. The possible aetiological importance of the urine flow rate is stressed. The presence of medullary urate deposits at autopsy was most frequently associated with a history of gout or the presence of pre-existing and non-gouty renal disease, although no aetiological factor could be determined in a quarter of the cases.