The aim of this study was to determine the clinical characteristics of Behcet's disease (BD) complicated with malignancy in Korea. Of 1,769 patients with BD in our hospital, 32 patients (1.8%, 21 in solid cancer, 11 in hematologic malignancy) developed cancer. In 10 of the 32 subjects (31.3%), malignancy was diagnosed before or concomitantly with BD. Twelve cases (37.5%) occurred within the first 2 years of disease and 9 cases (28.1%) occurred 5 years after the diagnosis of BD. Myelodysplastic syndrome (MDS) was the most common disease (n = 7) followed by thyroid cancer (n = 4), breast cancer, cervix cancer, stomach cancer, rectal cancer, hepatoma, aplastic anemia (n = 3, each), renal cell cancer, endometrial cancer, lymphoma (n = 1, each). There were no significant differences in the clinical characteristic between patients with or without malignancy. Intestinal involvement were more frequent in patients with malignancy than those without, but was not statistically significant (p = 0.083). Our results demonstrate that MDS and thyroid cancer are the most common hematologic disease and solid cancer associated with BD, respectively. Further studies will be required to ascertain the pathogenic link between BD and malignancy and the prevalence of malignancy in BD.