We report the findings of a critical evaluation of urological assessment in impotence. Initially, a rating scale (Q scale) was developed, which included the individual elements of the urological assessment, such as testicular size, serum testosterone level and so forth. The items in the scale were derived from the files of patients with erectile dysfunction and were scaled according to predetermined categories. Following this, the rating scale was applied to 67 impotent patients in whom the etiology had been established clearly using criteria that were independent of the urological assessment (that is a psychiatric interview and nocturnal penile tumescence evaluation). Statistical analysis of the results indicated that the 2 diagnostic groups differed significantly on a number of the individual scale items. However, no single item by itself could be used as a reliable indicator of etiology. Further analysis indicated that when the items were considered in combination, rather than singly, etiology was identified correctly in 95 per cent of the patients in the sample. Replication of these findings in a cross-validation study will help to standardize the urological assessment and to promote the development of a common language to facilitate communication in this field.