The expression of TSP-1 gene mRNA and TSP-1 protein in the placental tissue was studied during normal pregnancy and in gestosis. The formation of placental tissue in normal gestation was associated with expression of TSP-1 gene mRNA and of TSP-1 protein. Gestosis was associated with infl ammatory reaction in the placenta characterized by increased counts of lymphocytes and macrophages in the villous stroma and involution degenerative changes in tissue. Disorders in placental villi maturation and branching in gestosis were paralleled by hyperexpression of TSP-1 gene mRNA by placental cells and hyperexpression of TSP-1 protein predominating in the stromal elements of terminal villi and near villous vessels.