BACKGROUND Abnormalities in BMI are well documented in childhood cancer survivors. Perceptions of BMI status in cancer survivors have been understudied. This study determines the accuracy of parent/survivor and provider reporting of BMI status in a cancer survivor program. PROCEDURE This is a retrospective study. Parent/survivor assessment of BMI status was obtained from a baseline questionnaire of subjects enrolled in Children's Healthcare of Atlanta-Childhood, Adolescent, and Young Adult Cancer Survivor Study (CHOA-CAYACSS). Provider reporting of BMI was obtained from a clinic visit close in date to completion of the survey. Perceptions of BMI were compared to actual BMI status calculated from clinic visits and categorized based on the Centers for Disease Control and Prevention (CDC) BMI guidelines. RESULTS Perceptions of BMI were collected from 290 survivors of pediatric cancer or their parents (range, 4.3-22.9 years). Nearly 5% of survivors were underweight, 19.7% overweight and 16.2% obese. High BMI was the BMI state least likely to be correctly identified by parents, survivors, and providers. Among survivors with high BMI, parents, survivors, and providers failed to identify the problem 49.4%, 66.7%, and 26.9% of the time, respectively. Providers were less likely to correctly identify overweight compared to obese status (P < 0.0001). Accuracy of BMI recognition was independent of gender of survivor, ethnicity, or primary cancer diagnosis. CONCLUSION Abnormal BMI states, especially overweight, are frequently not correctly perceived by parents/survivors or providers. Assessment of BMI status and discussion about steps to normalize BMI is needed to prevent weight related morbidities in this population.