We investigated the prevalence of antinuclear antibody (ANA), thyroid antimicrosomal (AMA) and antithyroglobulin (ATA), antigliadin (AGA) immunoglobulin G (IgG)-A, anti-endomisium (EMA) IgG-A, and tissue transglutaminase (tTG) IgG-A in 87 patients with chronic idiopathic thrombocytopenic purpura (cITP) and in 95 healthy controls. Antinuclear antibody positivity was found in 13 of 87 patients and 3 of 95 controls (P = .007). Antithyroglobulin positivity was found in 27 of patients and in 7 of the controls (P < .001). AMA positivity was found in 20 of patients and 8 of the controls (P = 0.008). Antigliadin IgG was positive in 17 patients and 1 controls (P < .001) whereas Antigliadin IgA was positive in 9 of patients and in 1 of the controls (P = .007). Anti-endomisium (IgG and IgA were not different between both groups. Tissue transglutaminase IgG was detected in 7 of patients and in 1 of the controls (P = .029). Tissue transglutaminase IgA was detected in 5 of patients and in none of the controls (P = .023). We believe that larger studies are needed to determine the long-term impact and clinical importance of these autoantibodies.