Background: A common method used to examine the relationship between internal preferences and caring externalities is willingness to pay (WTP) approach. We aimed to estimate WTP for health status with different severity level and identify determinant factors on WTP. Methods: For determining main factors in WTP, a cross-sectional study was conducted in Shiraz in the southeast of Iran, in March to April 2015. The open-ended method was used to estimate monthly WTP in private and altruistic section. Multivariate regression analyses using ordinary least squares were applied to examine the effect of Scio-demographic factors on WTP using SPSS software 21. Results: Participants were willing to pay an average amount of $ 295 in health status 1 and an average amount of $ 596 in health status 6 (worst status) for internal preferences. Altruistic WTP for health status 1 was $ 294 and participants were willing to pay an average amount of $ 416 in health status 6. Multiple regression analysis identified monthly income as the key determinant of WTP for internal preferences and caring externalities (P < 0.01). With an increase of 1% in income, private WTP increase 1.38% in health status 1. Conclusions: The finding indicates that the mean of WTP increases at severe health status; therefore, health policy maker should allocate resources toward severe health status.