Pre-transplant conditioning regimens for bone marrow transplantation often cause oral mucositis and severe pain. We evaluated the agreement of self- and parent reports of daily oral mucositis pain in children between the ages of 6 and 16 years. Child patients were asked to report their pain on visual analog scales (VAS) daily for 20 days following their transplants. Daily VAS ratings were also obtained from one of the parents. The analysis sample consisted of ten children aged 7-9, nine children aged 10-12, eight children aged 13-16, and their parents. We modeled individual child and parent reports as quadratic functions of the number of days post transplant. Empirical Bayes/restricted maximum-likelihood estimates were obtained of individual coefficients, treated as random effects, and age group coefficients, treated as fixed effects. Parents exhibited higher average pain curves than their children in each of the three age groups. The middle age group reported the highest average pain. Average within-person error variances representing unreliability were 692.2, 461.9, and 303.9 for young, middle, and old children, respectively; for parents, the corresponding error variances were 375.1, 413.3, and 252.4. These results challenge the presumption that children tend to over-report pain but are consistent with the contention that younger children may be less reliable reporters than adolescents and adults.