Abstract: Micronucleus frequency (MNF) in peripheral blood lymphocytes was tested among 50 patients with liver cancer, 163 cases of first-degree relatives of liver cancer patients and 174 controls by micronuc leus technology to study the relationship between liver cancer and heredity. The results showed that there statistically significant differences between group of liver cancer patients controls and relatives of liver cancer patients (P<0.001).There was also a significant dif f rence among children, parents and siblings (p<0.05).MNF was found to be associated with consannguinity. MNF may be considered as a marker to assess the risk of cancer in different populations.