A numerical study of the evaporation by laminar natural convection of a heptane liquid droplet is presented. The classical boundary layer equations are used in the liquid phase and in the vapor phase. The transfers are described by the natural convection equations. The linkage between heat and mass transfer in the liquid and vapor phases is ensured by the continuity at the liquid vapor interface by the heat and mass flux densities and the shear stresses. Dimensionless equations in the liquid and vapor phases are solved using an implicit numerical scheme and Thomas algorithm. One analyzes the effects of the gaseous medium temperature and the initial droplet radius values on the profiles of the temperature and radial velocity in both phases, of the heptane vapor fraction in the gaseous medium and of the vapor phase thickness. Thus, the vapor phase thickness is calculated and presented versus time for different physical parameters especially the theta angle. The none-sphericity of the evaporated heptane droplet is clearly observed.