In this study, ELISA and VDRL tests have been employed in order to detect ACL antibodies in sera samples obtained from 105 patients with SLE, RA, scleroderma, dermatomyositis, primary Sjögren's syndrome, vasculitis and pulmonary thromboemboli; Using by IFAT, AMA-type 5 and other autoantibodies, RIA anti-DNA antibodies were also tested in SLE patients. In sera obtained from the patients with RA; autoantibodies and RF have been investigated. In SLE cases, ACL antibodies were found to be positive in 55.5% of the patients. In RA cases the rate of ACL antibodies were found to be 51.7%. In SLE cases, the presence of IgG-ACL antibody was found to be in association with thrombosis and fetal loss; while IgM-ACL antibody was found to be in association with fetal loss only. Serologic parameters such as VDRL and AMA type 5 were significantly connected with the presence of ACL-IgG and IgM antibodies (p less than 0.05). In cases of RA connection was detected only between IgG-ACL antibody and thrombosis. Concerning the other rheumatic autoimmune diseases; ACL antibodies were detected in cases: 4 patients out of 11 scleroderma, 1 patient out of 7 vasculitis, 2 patients out of 5 primary Sjögren's syndrome, and 3 patients out of 6 pulmonary thromboemboli.