**1. Introduction**

Retinoblastoma (Rb) is the most common intraocular malignancy of childhood, but a relatively rare disease, occurring in approximately 1: 16,000–18,000 live births [1]. Its incidence is uniform across populations, with no known gender, racial or ethnic predilection. Rb develops in early childhood, with the vast majority of cases that present before the age of 5 years. The disease can involve one or both eyes and can be inherited from an affected parent or developed *de novo* in a child with no family history of Rb. This chapter discusses the epidemiological aspects of Rb, including basic concepts in Rb development, incidence and prevalence, age, sex and racial considerations, associated environmental factors, trilateral Rb and secondary non-Rb malignancies.
