The addition of human foetal cord serum to the culture medium improves the in vitro growth of human chorionic villi cells. The expression of HCG, laminin, laminin receptor, and type IV collagen has been studied on first passage (4-7 weeks) cultured villi cells by the immunoperoxidase method. No cells were positive for HCG, while various patterns of basement membrane markers were always detectable. The presence of laminin and collagen type IV excludes fibroblast contamination and can be used for a rapid trophoblast cells identification.