The relationship between maternal caprine pregnancy-associated glycoprotein (cPAG) concentrations and fetal number was investigated in 21 nulliparous and 17 multiparous goats. Using a homologous radioimmunoassay (hm-RIA) cPAG was detected in plasma of pregnant goats from the 21st day of pregnancy. Statistical differences between goats bearing single and multiple fetuses were observed after 63 days to the end of pregnancy, except on day 133. After 126 days (3rd week pre-partum) cPAG levels began to decrease slowly in both the groups. The hm-RIA was an efficient method to describe the relationship between maternal PAO concentrations and number of fetuses in goats. (C) 2001 Published by Elsevier Science B.V.