AbstractEjaculates were obtained from eight adult male chimpanzees trained to use an artificial vagina. Spontaneously liquefied fractions were collected at 0–1, 1–2 and 2–4 h after ejaculation. The mean volumes of the spontaneously liquefied fractions did not differ significantly among the three fractions. The total number of sperm, the percentage of motile sperm and the percentage of live sperm decreased significantly (P<0.005) between the 0–1 and 1–2 h fractions. Citrate concentration and alpha‐glucosidase activity (mU/ml) decreased significantly (P<0.005) from 0–1 to 1–2 to 2–4 h fractions. The volume of the liquefied fraction correlated positively (P<0.001) with total protein and with total citrate at 0–1, 1–2 and 2–4 h. The total number of sperm correlated positively total with total alpha‐glucosidase activity at 0–1, 1–2 and 2–4 h. Among the biochemical parameters measured, total protein and total citrate correlated positively at 0–1, 1–