Abstarct: The present study was conducted with the aim of investigating the effect of behavioral biases on financial decisions with regard to the role of serial mediation of overconfidence and the effects of inclination. The research method of the present study was descxriptive-correlational. The statistical population of this study includes life insurance policyholders in Iraq in an unlimited number of people, so 384 people were selected as a sample using the Cochran formula. The research tool was a questionnaire, and for reliability, the Cronbach's alpha coefficient method was used, which the values of this statistic were obtained for all variables greater than 0.7, and as a result, the questionnaire has the desired reliability, and content and face validity were used to confirm the validity. For content validity, the questionnaire was provided to the professors and their opinions were applied. WarpPLS software was used to analyze the hypotheses and structural equation model. The research findings showed that behavioral biases, overconfidence have a significant impact on investment decisions, there is a significant indirect (negative) relationship, but the effects of inclination do not have a significant impact on the investment decisions of life insurance policyholders. Behavioral biases have a direct and significant impact on overconfidence, but behavioral biases do not affect the effects of inclination of life insurance policyholders. And overconfidence also plays a role in the effects of inclination of life insurance policyholders. Overconfidence mediates the relationship between behavioral biases and investment decisions, but the effects of inclination do not mediate the relationship between behavioral biases and investment decisions, and overconfidence and the effects of inclination do not serially mediate the relationship between behavioral biases and investment decisions.