Objective: To explore significance of anti-transcriptional intermediary factor 1-γ (TIF1-γ) antibody detection in diagnosing ermatomyositis (DM) malignancy or clinically amyopathic dermatomyositis (CADM) accompanied by malignancy diseases. Methods: A total of hospitalized 223 patients were enrolled at Department of Dermatology, Ruijin Hospital during Jan. 2016 to Dec. 2019, including 107 cases of adult DM, 102 cases of adult CADM, 5 cases of juvenile DM, and 9 cases of juvenile CADM. DM patients were divided into malignant DM group and non-malignant DM group, and so were the CADM patients. Enzyme-linked immunosorbent assay(ELISA) was used to detect serum anti-TIF1-γ antibodies in patients at first visit. The positive rates of anti-TIF1-γ antibody were compared between malignant DM group and non-malignant DM as well as between malignant CADM group and non-malignant CADM group. Results： It revealed that 35 adult DM and 7 adult CADM patients were diagnosed as having malignant neoplasia, and nasopharyngeal carcinoma, breast cancer and lung cancer were on the top three of cancer-associated myositis in our cohort, however, there was no malignancy detected in JDM and JCADM patients. Seventy-four (35.4%) adult patients had serum anti-TIF1-γ antibody detected, including 36 cased of DM (33.6%) and 38 cases of CADM (37.3%). Serum anti-TIF1-γ antibody was positive in 3 cases of JCADM (33.3%), but none in total of 5 cases of JDM. The positive rate of anti-TIF1-γ antibody in DM patients with malignant tumor was significantly higher than those without malignant tumor[26/35(74.3%) vs 10/72(13.9%), P<0.000 1]. The incidence of malignant tumor in patients with positive anti-TIF1-γ antibody was significantly higher than those with negative antibody[26/36(72.2%) vs 9/71(12.7%), P<0.000 1]. However there was no significant difference in the positive rate of anti-TIF1-γ antibody between patients with malignant tumor and without malignant tumor [4/7 vs 34/95(35.8%), P=0.420] in adult CADM. There was no statistically significant difference in the incidence of malignancy between anti-TIF1-γ antibody-positive and antibody-negative patients[4/38 (10.5%) vs 3/64(4.7%), P=0.420]. Conclusions： Serum anti-TIF1-γ antibody correlates with the occurrence of malignancy diseases in DM, but has no relationship with malignancy diseases in CADM. Thus, anti-TIF1-γ antibody might be the serum biomarker for DM associated with malignancy, and oncology screening should be intensified in adult DM patients with positive anti-TIF1-γ antibody.