Mucosal toxicity is dose limiting for etoposide. This may be related to the direct effects of etoposide on the mucosa. Twelve patients receiving etoposide 1800 mg/m2 as part of a myeloablative pre-transplant regimen were randomized to receive propantheline 30 mg or placebo orally every 6 h for six doses. Mucositis was less frequent (2 of 6 vs 5 of 6) and less severe (p = 0.05) in the propantheline arm. There were no differences in tumor response or survival between the two groups. Propantheline is an anticholinergic that causes xerostomia by decreasing salivation. Propantheline may reduce the salivary excretion of etoposide and could reduce its toxic effects on the mucosa. Propantheline is effective in reducing the incidence and severity of mucositis in patients receiving high-dose etoposide.