Background: Transplant coronary arteriopathy (TCAD) limits graft survival after heart transplantation in adult and pediatric heart transplant recipients. Intravascular ultrasound (IVUS) provides a highly sensitive technique to detect TCAD. However, its use to determine factors associated with TCAD in pediatric recipients has been limited and its utility in surveillance for symptomatic TCAD in this population is uncertain. Methods: One hundred fifty-eight IVUS studies from 66 patients (27 <1 year and 39 >1 year at time of transplant) were performed 12 to 144 months after transplantation within the routine surveillance for TCAD. Maximal intimal thickness (MIT) and intimal index (II) were measured, and the Stanford classification was utilized to grade overall severity of disease. Mixed repeated-measures linear regression models were used to investigate the main and interaction effects of age at transplant, age at time of study, time since transplant and rejection events. Results: Age at catheterization (p = 0.0002), transplantation at age >12 months (p = 0.014), increasing time after transplantation (p = 0.021) and the combination of late rejection and hemodynamic compromising rejection (p = 0.05) were significantly associated with increasing MIT. Age at catheterization (p = 0.0149), transplantation at age >12 months (p = 0.016), time from transplantation (p = 0.0076) and rejection with hemodynamic compromise (p = 0.01) were significantly associated with increased II. Nine patients developed evidence of severe (Stanford Class 4) TCAD by IVUS, but only 2 (22%) developed symptomatic TCAD, with a median follow-up of 44 months. Four of the 7 patients who developed symptomatic TCAD had no or minimal TCAD (Stanford Class 0 or 1) on a surveillance examination within 18 months of the onset of symptoms. Conclusions: Increasing time after transplantation, recipient age and age at transplantation as well as rejection history, especially rejection with hemodynamic compromise, are associated with the development of TCAD as detected by IVUS in pediatric heart transplant recipients. Severe TCAD detected by IVUS does not often rapidly progress to symptomatic TCAD. Symptomatic TCAD may develop rapidly even in patients with little or no TCAD detected by IVUS.