A sample relation is used to calculate the ionicity (fi) and microhardness of binary tetrahedral semiconductors. An investigation into various crystal parameters and their correlation have been done. Lavin's modification of Phillip and Van Vechten (PVV) theory are discussed and hence ionic gap (E_c), homopolar gap (E_h) average gap (E_p) and ionicity (f_i) are investigated for binary tetrahedral semiconductors. The estimated value of ionicity is then used to evaluate the values of microhardness. The results have been compared with corresponding values reported in literature. A fairly good agreement has been obtained between the results and values reported by other workers.