To discuss the importance of routine ophthalmic examination of parents and siblings of retinoblastoma (RB) patients. Prospective nonrandomized observational/interventional case series of consecutive families of 131 RB patients. Routine ophthalmic examination of families (parents and siblings) of 131 consecutive newly diagnosed RB patients, including 262 parents and 23 siblings, revealed spontaneously regressed RB in at least 1 parent of 10 (8%) patients and active RB in at least 1 sibling of 3 (2%) patients. Of the 10 parents with spontaneously regressed RB, the lesions were unilateral (n = 7) or bilateral (n = 3). The regression patterns (n = 13) were comparable with postirradiation regression patterns Type 1 (n = 3), Type 2 (n = 2), Type 3 (n = 2), and Type 4 (n = 3), and spontaneous phthisis bulbi (n = 3). Fundus screening of siblings revealed active RB in at least 1 sibling of 3 (2%) patients. Of these 3 siblings, 2 had unilateral and 1 had bilateral disease. The mean age at detection of RB was 15 months (median, 6 months; range, 2-36 months). The disease was unilateral in 2 and bilateral in 1 patient. Based on International Classification of Intraocular Retinoblastoma, the tumors (n = 4) were classified as Group A (n = 2) and Group B (n = 2). Routine fundus screening of siblings allows for early detection of RB in otherwise asymptomatic children. Detection of spontaneously regressed RB in parents may act as a surrogate marker for germline RB1 mutation and is helpful in genetic counseling.