Background: A number of studies have investigated the association between increased pretreatment serum C-reactive protein (CRP) levels and the prognosis of gastric cancer. However, due to the inconsistent results, whether the serum CRP level can be a prognostic factor in primary gastric cancer remains controversial. Methods: We searched Medline, PubMed, Embase and the Cochrane Central Register of Controlled Trials for relevant high-quality reports. A meta-analysis was carried out using the included studies to assess the association between pretreatment serum CRP level and overall survival (OS) in patients with gastric cancer. Correlation analyses were conducted to evaluate the relationship between serum CRP and tumor characteristics such as tumor node metastasis (TNM) stage and recurrence. Results: Twelve reports involving 2,597 patients with gastric cancer were included. Primary meta-analysis indicated a significant association between elevated CRP level and poor OS (HR 1.77, 95% CI 1.56-2.00). Subgroup analyses showed no single factor could alter the primary results when we divided the included studies by "number of patients", "max follow-up period", "TNM stage", "treatment" and "cut-off value". Correlation analyses showed that serum CRP level was significantly related to TNM stage (OR 2.96, 95% CI 2.22-3.93) and tumor recurrence (OR 1.81, 95% CI 1.21-2.71). Conclusions: We demonstrated that increased pretreatment serum CRP level (${geq}10mg/L$) was significantly associated with poor prognosis in gastric cancer patients, either in early or advanced stages.