We report that decreased expression of miR-30c in tumor compared to adjacent tissue is sex-dependent in colorectal cancer (CRC) patients. High expression of miR-30c was associated with better survival in the whole cohort. When the cohort was split into male and female subcohorts, decreased miR-30c expression in tumor compared to adjacent tissue was observed only in males. Expression of miR-30c was decreased in CRC tumor tissue in male patients with nodes involvement compared to those without metastases in nodes and this difference was not observe in females. Next dependency of miR-30c expression on oestrogen receptor β (ERβ) mRNA levels in tumor was tested. In males with low expression of ERβ, we observed a significant decrease in miR-30c levels in patients with nodes involvement compared to those without nodes involvement. This difference was not observed in males with high ERβ mRNA levels and in females. Accordingly, males with low expression of ERβ and high expression of miR-30c showed a better survival that those with low expression ERβ and low expression of miR-30c. It is possible to conclude that whole cohort survival dependence on miR-30c is mostly generated by a subcohort of males with low expression of ERβ mRNA in tumor tissue.