This study investigated the frequency of cancer-associated vasculitis, the types of associated cancers and vasculitides, and the temporal relationship in Korean patients who were diagnosed with both cancers and vasculitides. This study performed a digital search of the clinical data repository using selected diagnostic terms of vasculitides among patients diagnosed with cancers from May 2001 to May 2021. The time gap between the time of diagnosis of 'cancers' and that of 'vasculitides' was limited to 3years. The types of cancers and vasculitides were reviewed. The mean age of 73 patients with both cancers and vasculitides with a time gap of fewer than 3years was 53.0years and 42.5% were men. Of the 215,897 patients with cancers, 73 patients were also diagnosed with vasculitides (0.034%). The most common type of cancer was thyroid cancer (28.8%), followed by lymphoma (13.7%), whereas the most frequent type of vasculitis associated with cancer was Behcet disease (52.1%), followed by granulomatosis with polyangiitis (12.3%). The median time gap between cancer and vasculitis was - 17.0days. Among vasculitides, Behcet disease was closely associated with various cancers compared to other types. Twenty-one patients exhibited both cancers and vasculitides between 0 and 90days after the diagnosis of the corresponding cancer. The frequency of cancer-associated vasculitis was 0.034% in Korean patients. The types of cancers and vasculitides in cancer-associated vasculitis and the distributions of sex and age may be dependent on ethnic and geographic differences. Key Points âą The frequency of cancer-associated vasculitis was 0.034% in Korean patients. âą The most common cancer and vasculitis in cancer-associated vasculitis were thyroid cancer and Behcet disease. âą The types of cancers and vasculitides in cancer-associated vasculitis seemed to be dependent on ethnic and geographic differences.