Background: Sarcopenia was initially recognized as a marker representing the nutritional condition or aging. Recently, sarcopenia has been associated with a poor prognosis and postoperative complications. We examined the importance of sarcopenia as a predictive marker of the prognosis in penile cancer. Materials and Methods: A total of 25 patients diagnosed with penile cancer who underwent penile resection from 2000 to 2010 were analyzed in this study. The psoas muscle index (PMI) was calculated based on psoas area using preoperative axial computed tomography images at the right L3 level divided by the square of the body height. Results: Nineteen (76.0%) patients underwent partial penectomy, and 6 (24.0%) underwent total penectomy. The median (mean ± standard deviation) age was 69.3 (69.0 ± 10.1) years old. Regarding the site of penile cancer, 17 (76.0%) cases were in the glans, 6 (24.0%) were in the foreskin, and 2 (8.0%) were in the shaft. Lymph node metastasis were seen in 6 cases (24.0%), and distant metastasis was seen in 1 case (4.0%). The lower PMI group (< 320.0) showed a significantly poorer progression-free survival than the higher PMI group (≥ 320.0) (p = 0.030), although no significant difference in the overall survival was noted (p = 0.076). Conclusions: Sarcopenia might be a useful prognostic factor in penile cancer patients.