Intensive chemoradiotherapy damages the mucosal barrier of the mouth and throat and is often associated with severe oral inflammation and infection. This study examined the use of a 0.12% chlorhexidine gluconate mouthrinse for prophylaxis against oral complications in patients receiving bone marrow transplants. Use of chlorhexidine mouthrinse produced reductions in oral soft tissue disease and oral microbial burden, including a significant decrease in oral mucositis and Candida infections. The advantage for patients undergoing intensive antineoplastic therapy, and potentially for other immunocompromised patients susceptible to oral infections, was studied.