Semen was collected from ten intact male alpacas (five were adults and five were 3 years old) using an artificial vagina. Liquefaction of the viscous semen occurred within 24 h, after which samples were centrifuged at 3000 rev min-1 for 20 min before biochemical analysis. The average ejaculate volume was 1.7 ml; it was milky white in color, highly viscous and had slow mass motility. There were no significant differences in the concentrations of chloride, calcium, inorganic phosphate, phospholipids, total nitrogen, total protein and albumin between ages (P>0.05), with the exception of glucose and globulins concentrations. The mean concentrations of the components were chloride 376.0 mequiv 1-1, calcium 17.9 mg dl-1, inorganic phosphate 9.6 mg dl-1; glucose 6.2 mg dl-1, phospholipids 28.7 mg dl-1, total nitrogen 597.4 mg dl-1, total protein 3.7 mg dl-1, albumin 2.1 mg dl-1 and globulins 1.6 g dl-1, which is in close agreement with results for other species. © 1993.