Although not common, thrombotic thrombocytopenic purpura (TTP) is one of the most serious complications in patients with systemic lupus erythematosus (SLE). This study aimed to characterize the association between SLE and TTP by examining clinical features and treatment outcomes. We evaluated eight patients diagnosed over two years in our hospital. The mean disease duration of SLE until TTP onset was 13.2 years. One patient had a simultaneous diagnosis of SLE and TTP. CNS lupus and lupus nephritis were involved in 6 patients, respectively. The mean value of the SLE disease activity index was 40.5. Five out of 7 patients who have been examined the von Willebrand factor cleaving protease showed moderately decreased activity. Seven out of the 8 patients were treated with plasmapheresis, and 7 received immunosuppressive therapy including cyclophosphamide and rituximab. Seven patients recovered, but one died from an exacerbation of the disease. These data indicated that plasmapheresis and immunosuppressive therapy improved prognosis of TTP associated with SLE.