This report presents the results of visual observations of cavitation patterns on propellers for a tanker and a high speed cargo ship. Corresponding model tests have been carried out in the cavitation tunnel of the Ship Research Institute. Two kinds of wake distributions have been simulated in the tunnel for each propeller model, one of them being model wake and the other being full scale wake estimated by Sasajima's method (1). The greater stress has been laid on sketching the cavitation patterns and classifying the type of cavitation by visual observation than on photographing.