We describe a novel secreted protein, named hOLFML1 (human olfactomedin-like protein 1), with an olfectamine domain in its C-terminus, mainly expressed in the small intestine, liver, lung and heart. Immunohistochemical staining on human small intestine indicated that the protein localizes preferentially in the intestinal villi. Interestingly, ectopic hOLFML1 promoted proliferation of HeLa cells and increased the percentage of cells in S phase. In contrast, knock down of hOLFML1 protein expression by siRNA inhibited cell proliferation and delayed the entry of cells into S phase. Our data also revealed that hOLFML1 is N-glycosylated and its secretion is triggered by serum. Taken together, these findings suggest that hOLFML1 may play a significant role in the regulation of cell proliferation in vitro.