In this study we explain the cross section variability of intrastates income inequality which is measured by the Gird Index. The explanatory variables are the conventional ones which represent sociodemographic factors and the variance of human capital. The latter is measured by the Gini Index of years of school completed by the population 25 years and older. We estimate the model for four cross sections 1950, 1960, 1970 and 1980. We found that correcting for heteroskedasticity which is generated by the state and year effects on the variance of the random error improves the results significantly.