Summary:The purpose of our study was to describe the types and frequencies of altered dental development in pediatric patients preparing for bone marrow transplantation (BMT). Retrospective review of the medical records and panoramic radiographs of all patients who underwent BMT at St Jude Children's Research Hospital between 1990 and 2000 for whom pre-BMT dental examination and panoramic radiography records were available. All patients were treated on institutional protocols. We recorded patient demographics and radiographic evidence of microdontia, hypodontia, taurodontia, root stunting, caries, enamel pearls, and pulpal calcifications. The 259 patients identified (150 male and 109 female) had a median age of 12.82 years (range, 3.18-25.93 years) at the time of BMT. In total, 203 were Caucasian, 38 were African-American, and 18 were of other races. In all, 150 (57.9%) had abnormal dentition. The most common dental abnormalities were caries (n ¼ 84), pulpal calcifications (n ¼ 34), and dental extractions (n ¼ 33). Developmental abnormalities occurred less frequently: taurodontia (n ¼ 8), hypodontia (n ¼ 10), microdontia (n ¼ 11), and root stunting (n ¼ 11). Dental abnormalities are prevalent in children undergoing BMT. Pre-transplant oral hygiene and dental examination should be standard care in order to minimize potential sites of infection.