The effect of dental evaluation and treatment prior to bone marrow transplantation in 11 pediatric patients was assessed. Oral complications associated with marrow ablative therapy and the immediate posttransplant period (Days 0-35) were also studied. Oral complications during marrow ablative therapy included: xerostomia (2/11 patients) and parotitis (1/11 patients). Oral complications in the immediate post-transplant period (Days 0-35) included: mucositis (11/11 patients); moniliasis (9/11 patients); and stomatitis associated with acute G.V.H.D. (3/9 patients receiving allogenic marrow transplants). The onset of the mucositis in the posttransplant period usually occurred at the nadir of the white blood cell count and resolved when the absolute neutrophil count was approximately 500/m3. The onset of moniliasis in the posttransplant period was usually 1-2 days after the onset of the mucositis. Resolution of the moniliasis usually paralleled resolution of the mucositis. No patient developed an infectious and/or hemorrhagic complication of odontogenic origin.