Objective: To describe patient and ocular outcomes following initial treatment with external beam radiotherapy (EBT) in eyes with Reese-Ellsworth groupVb ret inoblastoma. Methods: Retrospective case series (from January 1, 1979, to Februa ry 28, 2002). The Kaplan-Meier method was used to analyze survival (ocular and patient) and incidence (second cancer)-data. Results: Two hundred forty-three patients with 1 or more Reese-Ellsworth group Vb eyes were identified. Of 284 g roup Vb eyes, 63 (22.2%) initially received EBT, vs 172 (60.6%) that were init ially enucleated. Of the 63 radiated group Vb eyes, 31 (49.2%) had no further t umor growth, 26 (41.3%) developed a recurrence, and 8 (12.7%) developed a new tumor. Of the 63 radiated group Vb eyes, 33 (52.4%) developed ocular complicati ons. The ocular survival rate of radiated group Vb eyes was 81.4%at 1 year and 53.4%at 10 years. Twenty-eight radiated group Vb eyes survived to the last fol low-up with visual acuity information. Thirteen patients developed second cance rs, 11 in the field of radiation. The probability of developing a second cancer following initial EBT for group Vb disease in patients with bilateral disease wa s 29.7%by 10 years after diagnosis. Survival from second cancers in patients wi th bilateral disease initially receiving EBT for group Vb disease was 93.6%at 5 years and 52.6%at 181/4 years. No patient with unilateral disease developed a second cancer. Deaths due to metastatic retinoblastoma were uncommon. Conclusion s: To our knowledge, this is the first study focusing exclusively on group Vb ey es treated initially with EBT, most of which were salvaged with vision. Outcome data provided herein are clinically relevant when choosing treatment options for advanced intraocular retinoblastoma. Objective: To describe patient and ocular patterns following initial treatment with external beam radiotherapy (EBT) in eyes with Reese-Ellsworth group Vb ret inoblastoma. Methods: Retrospective case series (from January 1, 1979, to Februa ry 28, 2002) -Meier method was used to analyze survival (ocular and patient) and incidence (second cancer) -data. Results: Two hundred forty-three patients with 1 or more Reese-Ellsworth group Vb eyes were identified. Of 284 g roup Vb eyes, Of the 63 radiated group Vb eyes, 31 (49.2%) had no further t umor growth, 26 (41.3%) developed a recurrence, Of the 63 radiated group Vb eyes, 33 (52.4%) developed ocular complicati ons. The ocular survival rate of radiated group Vb eyes was 81.4% at 1 year and 53.4% ​​at 10 years . Twenty-eight radiated group Vb eyes survived to the last fol low-up with visual acuity information. Thirteen p atients developed second cancers, 11 in the field of radiation. The probability of developing a second cancer following initial EBT for group Vb disease in patients with bilateral disease wa 29.7% by 10 years after diagnosis. Survival from second cancers in patients wi th bilateral disease initially receiving EBT for group Vb disease was 93.6% at 5 years and 52.6% at 181/4 years. No patient with unilateral disease developed a second cancer. Deaths due to metastatic retinoblastoma were uncommon. is the first study focusing exclusively on group Vb ey es treatment initially with EBT, most of which were salvaged with vision. Outcome data provided herein are clinically relevant when choosing treatment options for advanced intraocular retinoblastoma.