The aim of this study was to show the relation of platelet indices with the severity of acute pancreatitis (AP) and if they have any correlation with the severity of AP. Forty-seven patients with AP hospitalized in Department of Gastroenterology, Inonu University Faculty of Medicine were divided into two groups, namely, the severe AP group (n=15) and the mild AP group (n=32). The scores of these patients at days 0, 3 and at the beginning of remission according to the prognostic scoring systems (Ranson, APACHE II, and BISAP criteria), CRP, sedimentation and platelet indices (platelet count, MPV, PDW and PCT) were noted. Mann-Whitney U test was used to compare the groups. Spearman's Rho test was used to evaluate the correlations between the platelet indices and other prognostic factors. Significant differences were found between the groups as regards platelets (P<0.02), PDW (P<0.001), AST (P<0.001), ALT (P<0.001), Total bilirubin (P<0.007), LDH (P<0.001), CRP (P<0.001), sedimentation (P<0.001), APACHE-II (P<0.001), Ranson (P<0.002) parameters. When considered for the correlation between the platelet indices and other prognostic factors, it was seen that all the platelet indices showed strong positive or negative correlation in mild AP with other prognostic scoring systems, CRP and sedimentation. In contrast, it was seen that platelet indices in severe AP cases did not show strong correlation with other prognostic scoring systems, CRP and sedimentation. We showed that platelet derivatives can be used as a good prognostic biomarker for the course of mild AP. In severe AP cases, however, usability of platelet indices must be supported with further studies.