We have measured complex dielectric functions, epsilon (1) + i epsilon (2), of GaAs1-xNx alloys using spectroscopic ellipsometry to investigate higher-energy band gaps. The E-1 gap-related peak height for epsilon (2) decreases with increasing N concentration, indicating that the optical absorption at the E-1 gap decreases. On the contrary, the E-2 gap transition does not change so much with varying N concentration. These results are consistent with the theoretical study, which predicts that the lowest conduction band is mostly a combination of the Gamma and L states. The bowing parameters of the E-1 and E-2 yaps are rather large but much smaller than the bowing parameter of the E-o gap.