In recent years, an increase abundance and harmfulness of the San José scale (Comstockaspis perniciosa (Comstock, 1881) has been reported from many European countries. In Poland, C. perniciosa was not observed after 1948–1949, when it was first collected, until it was found again in 2015. It is considered as the most serious pest infecting many different species of plants worldwide. Basic diagnostic information for the San José scale and the key to identify similar diaspidid species recorded in Poland is provided. Current knowledge regarding the biology, host plants, distribution, and control, as well as information regarding the life cycle of C. perniciosa in Poland is summarized.