Patients who are scheduled to receive autologous or allogenic peripheral blood stem cell or bone marrow transplant will be invited to participate in this study during a regularly scheduled pre-treatment visit. Written informed consent will be obtained from all participants. Patients will be randomized to receive either etanercept mouthwash or placebo, which will both be administered by protocol schedule. Stomatitis and oropharyngeal pain will be measured at baseline and at specified post-chemotherapy time points corresponding with the predicted stomatitis onset, peak, and healing time course. TNF(alpha) levels in buccal mucosa, analyzed by reverse transcriptase polymerase chain reaction techniques, and blood levels of pro-inflammatory cytokines, growth factors, and inflammatory mediators will also be measured at baseline and at specified post-chemotherapy time points corresponding with the predicted stomatitis onset, peak, and healing time course.