Background/Aims: The aim of the present study is to evaluate the prognostic factors and efficacy of adjuvant chemotherapy in stage IIA colon cancer patients. Methodology: From 1994 to 2004, we retrospectively analyzed 447 patients with stage IIA colon cancer. The patients were divided into the surgery only and the surgery with adjuvant chemotherapy. The reviewed factors were age, gender, the size of tumor, differentiation, the number of harvested lymph nodes, lymphovascular invasion, perineural invasion and obstruction. Results: Of the 447 patients, 351 patients (78.5%) received the adjuvant chemotherapy and 96 patients (21.5%) underwent the surgery alone. The significant predictors of survival were lymphovascular invasion (p=0.045) and adjuvant chemotherapy (p<0.001) on the multivariate analysis. For the recurrence, male (p=0.014), the number of harvested lymph node (>= 5 vs. <15) (p=0.021), lymphovascular invasion (p=0.050) and adjuvant chemotherapy (p=0.049) were significant on the multivariate analysis. There were similar therapeutic efficacy for survival and recurrence among 5-fluorouracil, capecitabine and uracil/tegafur (p=0.854 and p=0.937, respectively). Conclusions: Lymphovascular invasion and adjuvant chemotherapy were independent prognostic factors. Adjuvant chemotherapy was effective in preventing recurrence and improving survival for the stage IIA colon cancer patients, especially for those patients with less than 15 harvested lymph nodes.