The band cap bowings of InNxAs1-x, InNxSb1-x, and InAsxSb1-x alloys defined by the optimized lattice constants are investigated using empirical tight binding (ETB) method. The present ETB energy parameters which take the nearest neighbor interactions into account with sp(3)d(2) basis are determined to be sufficient to provide a typical feature for the band gap bowings of the alloys. The band gap bowing parameter is found to be relatively large in both InNxAs1-x and InNxSb1-x compared to InAsxSb1-x alloys. Moreover, the variation of the fundamental band gaps of InNxSb1-x alloys is sharper than that of InNxAs1-x alloys for small concentrations of N. Besides, a small amount of nitrogen is determined to be more effective in InNxSb1-x than in InNxAs1-x alloys to decrease the corresponding effective masses of the electrons around Gamma points. (C) 2008 Elsevier B.V. All rights reserved.