The content of nuclear androgen receptors (ARn) in prostatic carcinoma biopsies is not predictive for the duration of response of the tumor to endocrine therapy. Recently pre-treatment plasma testosterone has been suggested to be predictive in this respect. Therefore, pre-treatment plasma testosterone (T) and sex hormone binding globulin (SHBG) levels were studied in 31 patients aged 72 +/- 10 years (range: 45-87) with stage D2 carcinoma of the prostate treated by orchiectomy. In 26 of these patients, the ARn level of the carcinoma was also known (61 +/- 41 fmol/mg protein; range 0-169). Plasma T levels (mean: 13.7 +/- 6.1 nmol/l) varied widely (range: 2.4-25.4), as did plasma SHBG (32.5 +/- 19.3 nmol/l; range 4.4-78.8), and time to progression (TTP; 14.6 +/- 11.2 months; range 1-48). Plasma T was found to be correlated to age (Rs = 0.537; P less than 0.01) and TTP (Rs = 0.4495; P less than 0.02). Tissue ARn and plasma SHBG did not correlate to any of the parameters studied.