The daily urinary excretion of calcium, oxalate, uric acid and glycosaminoglycans, and 24-h urinary volume and pH, were measured in 39 normal men and 65 male patients who had formed at least one calcium oxalate stone. No significant difference could be found between the two groups of subjects with respect to any of the urinary parameters. Nonetheless, a higher proportion of stone-formers than normals had daily excretion levels of oxalate in excess of the normal 95th percentile. On the other hand, there was no difference between the proportion of stone-formers and normals who fell into this category with respect to calcium excretion. It was concluded that a single 24-h urine analysis is of limited practical value in explaining the occurrence of stones or in predicting the likelihood of further episodes in unselected stone-formers attending a general hospital outpatient clinic.