INTRODUCTION: To evaluate whether varying degrees of seminomatous elements in the primary orchiectomy specimen would be predictive of patient morbidity during post-chemotherapy retroperitoneal lymph node dissection (PC-RPLND) since the desmoplastic reaction with seminoma is associated with increased intraoperative complexity. MATERIALS AND METHODS: We retrospectively identified 127 patients who underwent PC-RPLND for residual retroperitoneal masses. Clinicodemographic, intraoperative, and 30 day postoperative outcomes were compared for patients with pure seminoma (SEM), mixed germ cell tumors (GCT) containing seminoma elements (NS+SEM), and tumors with no seminoma elements (NS). Multivariate logistic regression was used to determine independent predictors of intraoperative and postoperative 30 day complications. RESULTS: We excluded 19 patients who received chemotherapy prior to orchiectomy, 2 patients with primary extragonadal GCT, and 3 patients who underwent re-do RPLND, leaving 103 patients for analysis. Fourteen patients (13.6%) had SEM, 18 (17.5%) had NS+SEM, and 71 (68.9%) had only NS elements. SEM patients were older (p = 0.03), had more intraoperative blood loss (p = 0.03), and were more likely to have residual seminomatous components in their post-chemotherapy lymph node (LN) histology (p = 0.01). Percent seminoma in the orchiectomy specimen was an independent predictor of estimated blood loss > 1.5 liters (odds ratio: 1.04, 95% confidence interval: 1.01-1.07; p = 0.013) after adjusting for age, stage, IGCCC risk category, preop chemotherapy, number and largest LN removed, need for vascular or adjacent organ resection (including nephrectomy), and LN histology.