Introduction: Placenta growth factor (PlGF), a member of the VEGF family of proangiogenic proteins, plays a role in pathological angiogenesis; tissue expression levels are elevated in numerous malignancies and, in colorectal cancer (CRC), correlate with tumor stage, vascularity, and survival. Plasma PlGF levels in cancer patients have not been well studied. The purpose of this study was to evaluate plasma PlGF levels in patients with CRC or benign colonic conditions and to determine if there is a relationship between blood levels and tumor (T), nodal (N), or final tumor stage.Methods: Preoperative blood samples as well as demographic, clinical, and pathology data were obtained from patients undergoing colorectal resection for benign and malignant conditions. PlGF plasma levels were determined via ELISA in duplicate and are reported as mean ± standard deviation. The t test was used to compare PlGF levels between groups while the ANOVA test was used to assess the relationship between PlGF levels and T, N, or tumor stage in the cancer group. Significance was defined as p<0.05.Results: A total of 124 CRC (80% colon, 20% rectal) and 111 patients with benign conditions (46% adenomas, 47% diverticulitis) were studied. The mean preoperative plasma PlGF level was significantly higher in the cancer group (15.7 pg/ml ± 5.3) than in the control group (13.5pg/ml± 5.5); (P= 0.001). There was no significant difference in levels noted between the rectal and colon cancer subgroups. Of note, no significant correlation between plasma PlGF levels and T or N stage was found although plasma levels were higher in node positive patients. Conclusion: There is a modest (16%) but significant increase in mean plasma PlGF levels in CRC patients when compared to levels in patients with benign colonic disease. It is assumed that the tumor is the source of the additional PlGF found in the blood. Unfortunately, no relationship was found between plasma PlGF levels and either the T, N, or final tumor stage. It is not likely that blood levels of PlGF alone will be useful in staging or evaluating CRC patients.