Maximum tumor diameter (DMAX) is considered by many Authors as an im prognostic factor in gastric cancer (GC) correlated with tumor depth (pT). Aim of this retrospective study was to evaluate the prognostic value of DMAX and its predictive role of tumor stage in a series of 164 gastric cancer patients. One hundred and sixty-four patients underwent gastrectomy between January 1994 and December 2004. DMAX value was measured on resected specimens fixed in 10% formalin solution with cut-off of 40 mm. Tumors according to these measurements were classified in DMAX1 < or = mm and DMAX2 >40 mm. The prognostic significance of DMAX along with other factors was evaluated with log-rank test and Cox regression. The correlation between DMAX and other variables was calculated by Spearman test. Overall 5-year survival rate is 56.6%. DMAX resulted significantly linked to survival at univariate analysis (p = 0.0001). The Spearman correlation test showed that DMAX is strongly correlated with tumor stage (positive predictive value of 88.5%), pT, pN, residual of tumor and grading. Our results showed that patients with large tumor at an increased risk for tumor advancement and, therefore, DMAX could represent a useful parameter for selection of patients for neoadjuvant protocols.