Tumor-associated macrophages are known to be associated with decreased survival of patients with endometrial cancer. Given the physiological link of circulating monocytes as a progenitor of tumor-associated macrophages, monocyte counts were examined for tumor characteristics and survival in endometrial cancer.A retrospective study was conducted to examine consecutive patients with endometrial cancer with all histologic types who underwent hysterectomy-based surgical staging between 2003 and 2013 (n=541). Preoperative monocyte counts were correlated to patient demographics, pathological findings, complete blood count results, and survival outcomes.Median monocyte counts were 0.5×109/L. Monocyte counts significantly correlated with all other complete blood count components, with neutrophil counts having the most significant association (r=0.52, p<0.001). Elevated monocyte counts (defined as >0.7×109/L) when compared to lower counts were significantly associated with an increased risk of >50% myometrial tumor invasion (29.2% versus 22.0%, odds ratio [OR] 1.59, 95% confidence interval [CI] 1.01–2.45, p=0.045), pelvic lymph node metastasis (39.0% versus 18.8%, OR 2.76, 95%CI 1.35–5.62, p=0.007), and advanced-stage (stage I through IV, 18.5%, 24.6%, 32.5%, and 41.5%, p=0.001). In survival analysis, elevated monocyte counts were associated with decreased disease-free survival (5-year rates, 71.0% versus 84.5%, p=0.001) and overall survival (77.2% versus 89.3%, p<0.001). In multivariate analysis, elevated monocyte counts remained an independent prognostic factor for decreased disease-free (hazard ratio [HR] 1.74, 95% CI 1.02–2.96, p=0.041) and overall (HR 2.63, 95% CI 1.37–5.05, p=0.004) survival.Elevated monocyte counts were associated with aggressive tumor features and poor survival outcomes of patients with endometrial cancer.