The aim of this study is to evaluate the ultrasonographic aspects of primary choroidal malignant melanoma (PCMM) after proton beam irradiation therapy and the reliability of its ultrasonographic follow-up in a series of 10 patients. All patients were examined with standardized A and B scan ultrasonography before and after treatment with proton beam irradiation therapy. The follow-up was carried out at 1, 3, 5, 8 months and then every 6 months. The mean follow-up was 20 months (range 6-34 months). The thickness of the tumors was demonstrated to be decreased and the internal reflectivity to be enhanced in 9 out of 10 cases from 8 months after treatment till the end of the follow-up period. Histopathology confirmed in 1 eye enucleated 5 months after treatment that medium-low internal reflectivity coresponded with several areas of high cellularity and cellular mitosis. The results of our study indicate the reliability of standardized A and B scan echography in the follow-up of PCMM treated with proton beam irradiation therapy.