Abstract: To evaluate the public health impact of association between prevalence of GSTM1 and GSTT1 null genotypes and age-standardized cancer mortality rate the present study, using data of 45 countries from five continents was done. Data of prevalence of GSTM1 and GSTT1 null genotypes was obtained from published articles in scientific journals. Data about the age-standardized mortality rates due to cancers (per 100,000 population) (for 2002) and total expenditure on health at international dollar rate per capita (for 2003) were obtained from the World Health Organization Web site http://www.who.int. In order to rule out the possible confounding effect of total expenditure on health per capita on the mortality rate, partial correlation analysis was carried out. After controlling the total expenditure on health per capita, significant positive correlation between prevalence of GSTM1 null genotype and age-standardized cancer mortality rate was observed (r = 0.301, df = 42, p = 0.047).