ABSTRACT We reported here three cases of osteogenic sarcoma after the treatment for retinoblas toma.

The first case was a girl with unilateral retinoblastoma and had been treated with enucleation and combined chemotherapy and external irradiation since she was 1 8/12 year old. The osteosar coma of right maxillary bone developed 8 1/2 years later. The second case was a girl with bilateral retinoblastoma and was treated with enucleation of her right eye and photocoagulation of her left eye since she was ten months old. Her mother refused to have any further therapy neither chemo therapy nor radiotherapy. The osteosarcoma of left lower limb was diagnosed by X-ray 7 years later. The last case was a boy with bilateral retinoblastoma whose both eyes were enucleated and had been treated with both chemotherapy and radiotherapy since he was 1 9/12 year old and osteos arcoma of left mandible occurred 3 years later.

In this series the osteosarcoma developed in both unilateral and bilateral retinoblastoma, and also in whom with or without radiotherapy. Longterm follow up is imperative in retinoblastoma survivors in order to detect late-development second malig nancies.