We found that the expression level of HDAC1 in gastrointestinal malignancies, especially in colorectal cancer (OR = 10.84, 95% CI = 5.33–22.07, P< 0.00001), was higher than that in noncancerous tissue, and HDAC1 expression was closely associated with some clinical features of gastrointestinal cancer patients, such as tumor stage (OR = 1.62, 95% CI = 1.28–2.05, P < 0.0001) and tumor grade (OR = 1.75, 95% CI = 1.03–2.95, P = 0.04). This evidence concerns the gene HDAC1 and neoplasm.