A study was performed on the distribution of catecholamines (noradrenaline, dopamine and adrenaline) and L-DOPA in the hypothalamo-hypophysial region, as well as in the region of n. caudatus, which participate in the control of sexual activities in sheep. After isolation in the activated aluminium oxide, the catecholamine concentration was determined spectrophotometrically. Hypothalamus was divided into three regions: rostral, medial and caudal. In the same regions of the cerebroneural system (CNS), the activity of the degradation enzyme monoaminooxidase (MAO) was determined by radiochemical method. 14C-tryptamine was as a substrate and the results were measured by means of scintillation spectrophotometer Packard. The distribution of catecholamines and L-DOPA in the hypothalamus of sheep is different. The largest proportion is that of noradrenaline in caudal hypothalamus (1.84 +/- +/- 0.36). The dopamine levels in hypothalamus are quite balanced though substantially lower than those of noradrenaline (from 0.22 to 0.31 micrograms/g). The concentrations of adrenaline and L-DOPA in the sheep hypothalamus are low. The sheep hypophysis contains more noradrenaline (1.70 +/- 0.38), adrenaline content amounts to 1.30 +/- 0.28. L-DOPA and dopamine occur in this region at low concentrations. In comparison with the other regions of sheep brain, high dopamine concentrations (2.0 +/- 0.58 micrograms/g) and higher L-DOPA levels were determined in n. caudatus. The activity of the degradation enzyme monoaminooxidase in the cerebroneural system of sheep is different. The highest MAO activity was determined in the rostral hypothalamus (1100 pmol X mg-1 X min-1), lower in its caudal and medial region.(ABSTRACT TRUNCATED AT 250 WORDS)