Retinoblastoma (RB) derives from loss or inactivation of both alleles of the normal retinoblastoma gene, a DNA sequence located on the long arm of chromosome 13 (q14 region). The occurrence of the loss or inactivation of the 2 normal alleles can determine if the disease is germline (that can be inherited by the descendants of a sick person) or somatic (that is not inherited by the descendants of a sick person). Advances in understanding of the different types of RB1 mutations (e.g. low penetrance mutations, somatic mutations, splice mutations) may facilitate determination of prognosis. RB derives from loss or inactivation of both alleles of the normal RB gene, a DNA sequence located on the long arm of chromosome 13. Leukocoria, strabismus and inflammatory signs are the most common findings on kids affected by RB. A relevant role in RB screening is performed also by relatives, who can detect leukocoria or strabismus just looking at their baby or noticing something abnormal in close-up pictures. Nowadays, many high sensitivity and specificity tests are available for genetic screening and counseling. Genetic counseling offers patients and relatives all the information, risks and elements necessary to make appropriate decisions.