The larval stages of the Pacific Brown Shrimp Penaeus californiensis HOLMES reared in the laboratory are described and illustrated, and a comparison is made with those of the Penaeus shrimps, P. japonicus and P. monodon. While the larvae of P. californiensis are morphologically simillar to those of P. japonicus and of P. monodon, and reach the fist postlarva passing 6 nauplial, 3 protozoeal and 3 mysis stages like these shrimps, there are some difference among them in size, form and setal arrangement.