PURPOSE Tumor deposits (TDs) seem to affect the prognosis of patients with colon cancer (CC). In the seventh edition of the American Joint Committee on Cancer TNM staging system for CC, the presence of TDs is only considered in the absence of lymph node metastases (LNMs). In the era of personalized duration of histopathologic criteria-based adjuvant therapy, this could potentially lead to a decrease in the prognostic prediction accuracy. PATIENTS AND METHODS A post hoc analysis of all pathologic reports from patients with stage III CC included in the IDEA France phase III study (ClinicalTrials.gov identifier: NCT00958737 ) investigating the duration of adjuvant fluorouracil, leucovorin, and oxaliplatin or capecitabine and oxaliplatin therapy (3 v 6 months) was performed. The primary objective was to determine the prognostic impact of TD on disease-free survival (DFS). The effect of the addition of TD to LNM count on pN restaging was also evaluated. A multivariable analysis was performed to establish the association between TD and DFS. RESULTS Of 1,942 patients, 184 (9.5%) had TDs. The pN1a/b and pN1c populations showed similar DFS. TD-positive patients had worse prognosis compared with TD-negative patients, with 3-year DFS rates of 65.6% (95% CI, 58.0% to 72.1%) and 74.7% (95% CI, 72.6% to 76.7%; P = .0079), respectively. On multivariable analysis, TDs were associated with a higher risk of recurrence or death (hazard ratio [HR], 1.36; P = .0201). Other adverse factors included pT4 and/or pN2 disease (HR, 2.21; P < .001), the 3 months of adjuvant treatment (HR, 1.29; P = .0029), tumor obstruction (HR, 1.28; P = .0233), and male sex (HR, 1.24; P = .0151). Patients restaged as having pN2 disease (n = 35, 2.3%) had similar DFS as patients initially classified as pN2. CONCLUSION The presence of TDs is an independent prognostic factor for DFS in patients with stage III CC. The addition of TD to LNM may help to better define the duration of adjuvant therapy.