This document provides an introduction to the genetics of retinitis pigmentosa (RP). It summarizes that RP affects between 1 in 3500 and 1 in 4000 individuals in the US. RP can be inherited in different patterns such as autosomal dominant, autosomal recessive, or X-linked. Genetic testing informs on the inheritance pattern and over 35 genes have been identified that can cause RP. The benefits of genetic testing include determining the underlying cause, eligibility for clinical trials, and clarification of recurrence risks.