We estimate Bohr radius and binding energy of exciton in bulk as well as quantum well for semiconductors with non-parabolic energy band structure. Kane type dispersion relation is used to incorporate such band non-parabolicity. Exciton binding energy in various III-V semiconductors are calculated for two different expressions of non-parabolicity factor α, and results are compared with those for parabolic energy bands. In presence of band non-parabolicity, exciton binding energies are found to increase in quantum wells, whereas such variation is almost insignificant in bulk semiconductors.