Capillary blood flow (133xenon clearance), deep testicular and muscle temperature (needle thermistor) and androgenic hormone concentrations in peripheral blood samples (RIA) were measured and the histology (needle biopsies) evaluated in 16 anaesthetized, mature Göttingen mini pigs. The blood flow was 0.26 +/- 0.10 ml x g-1 x min-1. The testicular temperature was 33.6 +/- 1.4 degrees C, and the body temperature 37.2 +/- 0.9 degrees C. The plasma levels of testosterone were 15.2 +/- 10.1 nmol x l-1, of dihydrotestosterone 0.99 +/- 0.98 nmol x l-1, dehydro-epi-androsterone sulphate 441 +/- 333, nmol x l-1, and the delta-4 androstenedione level was 9.2 +/- 7.0 nmol x l-1. Sexual-hormone-binding-globulin was immeasurable. The histological appearance was judged to 7.8 +/- 1.0 by a testicular biopsy score (scale 10-1). The results from the present investigation are in the same range of order as in other mammals and it is concluded that the mature, male Göttingen mini pig is a useful model for reproductive research.