The epididymal and seminal vesicular contributions to split-ejaculate fractions from boars were analysed for sperm concentration, glycerylphosphorylcholine (GPC), total-N, ethanol-soluble and insoluble N, citrate, zinc and haemagglutinin. The same components were also determined in epididymal plasma (EP), vesicular secretion (VS) and whole seminal plasma (SP). Isoelectric focusing of protein patterns was studied in the fractions. With the exception of haemagglutinin, the components were present to a major extent in either VS or EP and in lower concentrations in the other secretion. The parameters in VS or EP were positively correlated among themselves and negatively correlated with most of the parameters of the other fluid. The correlation coefficients were not significant in all cases for individual animals, but the degree of significance was greater for the over-all correlations. The EP components were mainly secreted in the first three or four fractions, but occasionally from fraction four onwards. Those of VS were emitted during the entire ejaculation, the maximum occurring in the sperm-rich fraction or the immediately succeeding fraction. The first fractions were devoid of VS components in only one case. The majority of the EP proteins could be identified electrophoretically in the sperm-rich fractions, but the protein patterns in the other fractions were similar to those of VS. The results are discussed and compared with previous findings.