The aim of the present review is to summarize the achievements on pregnancy-associated glycoproteins in sheep during the last 20 years on terms of results obtained after purifications, molecular biology, radio-immunoassays (RIA), enzyme linked immune sorbent assay (ELISA), double radial immune-diffusion (Ouchterlony) and Western blot techniques. The analysis of documented papers that concerned these attempts showed that the animal genetic material used was composed of variable breeds from north Africa, Europe and USA (the Aragonesa, Ouled Djellal, Laucaun drairy sheep, Berrichone, Texel x Norvegian crossed ewes, Awassi x Merino, Blackheaded Moutton sheep x Blackheaded German Mutton sheep (BGM), Rhoen sheep crosses of BGM with Dorper sheep, Assaf, Chura, Merino, Texel, Suffolk, Boujaâd Moroccan breed). The RIA represents the wildspread technique used (54%) while Oucherlony and Western blot had been limited in use (4% each). From 1990 to 2000 only 27% of the achievements being available today were realized. The main data, profiles and studies were performed from 2000 to now (63%). To conclude, this review allows summarizing and updating the knowledge about the PAG in sheep.