Sulfated glycosaminoglycan (GAG) composition was characterized in the human endometrium during proliferative and secretory phases of the menstrual cycle. Sulfated GAGs were analyzed in endometrium tissue using metachromatic staining, biochemical analysis including electrophoresis before and after specific enzymatic or chemical degradations, and immunostaining with an antibody against chondroitin sulfate (CS). Our results showed that CS was the main sulfated GAG species detected, accompanied by small amounts of heparan sulfate and dermatan sulfate. CS was distributed overall the connective stroma, around arteriole vessels and glands, and there was no important difference in the immunostaining between the proliferative and secretory endometrium phases. Our findings extend previous observations on the GAG composition in the human endometrium providing new information regarding the tissue distribution and location of endometrial CS.