: In 32 subjects with histologically and/or cytologically verified prostatic cancer the hormonal pattern was studied by assaying 18 plasma and urinary hormones or groups of hormones. The tumours were classified according to the UICC classification system and the hormone values were correlated to the local extent of the tumour (T classification), the presence of metastases (M classification) and the differentiation grade (G classification). It was found that patients with metastases had significantly higher plasma oestradiol and lower testosterone/oestradiol and testosterone/oestrone plus oestradiol ratios as compared to those subjects without metastases. In subjects with moderately or poorly differentiated tumours plasma oestrone + oestradiol was significantly higher and the testosterone/oestrone + oestradiol ratio was significantly lower than in the subjects with well differentiated tumours. In the various TNM classification groups no obvious trends were found with regard to urinary hormones and no significant differences between the groups for plasma FSH, LH, prolactin, progesterone and cortisol were observed. It is concluded that in more advanced cases with metastatic cancer and when tumours are less well differentiated the androgen/oestrogen ratio may be decreased. These alterations have no diagnostic significance because of great overlapping of individual results between the various groups of patients.