Abstract The isolation of 11β-hydroxyandrostenedione and 11β-hydroxytestosterone from testicular vein blood of the mature male domestic pig is described. Blood was collected from veins and arteries on the surface of the testes of mature boars. Steroids were extracted from plasma with SEP-PAK C 18 cartridges and recovered with acetonitrile. A separation of steroids was made by high performance liquid chromatography (HPLC) using acetonitrile/water ( 37 63 ; v/v ), and fractions were collected manually with detection at 254 nm. Preliminary identification was based on comparison with the HPLC retention time of an authentic steroid standard. Final characterization was achieved by means of capillary gas chromatography-mass spectrometry (GC-MS). The findings record the first evidence for the secretion of C 19-11-hydroxylated steroids by normal testes in a mammalian species.