This paper uses the British Health and Lifestyle Survey (1984-1985) data and the longitudinal follow-up of May 2003 to investigate the de- terminants of premature mortality risk in Great Britain. A behavioral model, which relates premature mortality to a set of observable and unobservable factors, is considered. We focus on unobservable indi- vidual heterogeneity and endogeneity a®ecting the mortality equation. A MSL approach for a multivariate probit (MVP) is used to estimate a recursive system of equations for deaths and lifestyles. This model is then compared with the univariate probit models that include or exclude lifestyles. In order to detect inequality in the distribution of health within the population and to calculate the contribution of socio- economic factors, we compare the range measure of health inequality to the Gini coe±cient for overall health inequality. A Gini decomposi- tion analysis for predicted premature mortality shows that endogenous lifestyles and unobservable heterogeneity strongly contribute to inequal- ity in mortality, reducing the role of socio-economic status