Cochlospermum tinctorium A. Rich. (Cochlospermaceae) is a widely used medicinal plant in the West African country, Mali. An ethnopharmacological survey was conducted and 106 traditional practitioners interviewed. The roots were the part of the plant reported to be the most frequently used for medicinal purposes. The main indications were to treat jaundice (41), gastro intestinal diseases or ailments (28), malaria (12), schistosomiasis (10) and dysurea (6). A high-molecular weight water extract (25, 50 and 100 mg/kg, body weight) significantly inhibited HCl/ethanol-induced gastric lesions in mice. The extract showed DPPH-radical scavenging- and immunomodulating activities in vitro. The main components of the extract were identified as polysaccharides (59.3%) and polyphenols (9.3%). The polysaccharides were purified and characterised as highly complex pectic arabinogalactans type II. As parts of the polyphenol compounds gallotannins and ferulic acids were identified. This study shows that the polysaccharides are partly responsible for the bioactivities observed in vitro. Both polysaccharides and polyphenols may be responsible for the anti-ulcer activities observed.