Objective: This study focused on decline in life expectancy situation in Nigeria from the perspective of health risk behaviours (HRBs) factors among secondary school students in Okitipupa Local Government Area, Ondo state. Methodology: Seven research hypotheses, based on the selected variables, were tested. The descriptive survey research design was adopted for the study; the multi-stage and stratified sampling techniques were used to select seventeen (17) public schools and one thousand three hundred (1300) senior secondary school students who are the participants for the study and a closed-ended self-structured questionnaire was employed for data collection. The descriptive statistics of frequency counts and percentages were used for the demographic data 2 while inferential statistics of chi-square (x ) was employed to test the hypotheses formulated at 0.05 alpha level. Results: The results of the study reveal that gender, religious belief and isolation were not significant (p<0.05) rather festival practices, parental influence, peer pressure and civilization/modernization were significant HRB factors among secondary school students Okitipupa Local Government Area of Ondo State, aiding decline in life expectancy. Conclusion: Life expectancy decline may pragmatically minimized when parents are made to religiously play their roles in the lives of youngsters through periodic health risk behavioural intervention programmes that centered on the activities of the secondary school students. Additional research may further the understanding of the debilitating effects of these health risk behaviors and facilitate development of effective increase in life expectancy.