We investigated the possibility that extracorporeal high energy shock wave (HESW) treatment of solid tumors increased metastatic tumor cell spread using a rapidly metastasising rat prostate tumor variant (R3327-MatLyLu). Volume of HESW treated primary tumor, the volume of metastatic lymph nodes and the number of lung tumor nodules formed were compared with values in untreated control rats. HESW treatment resulted in marked hemorrhage and readily visible hematoma at the focal point of treatment. Tumor histology directly after treatment showed extravascular blood cells due to breakage of blood vessels. Contrary to previous reports we could not observe a delay in tumor growth rate in either small or medium sized tumors. More importantly the extent of metastatic spread was not influenced by HESW treatment.