Abstract: Provided is a pharmaceutical composition for use in a method of preventing or treating a urinary tract infection (UTI), chronic cystitis, overactive bladder, partial bladder obstruction or urethritis, said composition comprising one or more oligomeric tannins, selected from proanthocyanidins and/or hydrolysable tannins, where in said method said composition is administered intraurethrally, intravesically, intraureterally and/or intrarenally, as well as a pharmaceutical composition for use in a method of preventing or treating bladder cancer, where in said method said composition is administered intravesically, said composition comprising one or more oligomeric tannins, selected from proanthocyanidins and/or hydrolysable tannins, wherein said tannins are optionally bound to an anti-cancer agent and/or liposomes containing an anti-cancer agent, together with compositions related thereto.