Metastable zinc blende CuInSe2 nanocrystals were synthesized by a hot-injection approach. It was found that the lattice mismatches between zinc blende CuInSe2 and ZnSe as well as CuInSe2 and CuInS2 are only 2.0% and 4.6%, respectively. Thus, alloyed (ZnSe)(x)(CuInSe2)(1-x) and CuInSexS2-x nanocrystals with a zinc blende structure have been successfully synthesized over the entire composition range, and the band gaps of alloys can be tuned in the range from 2.82 to 0.96 eV and 1.43 to 0.98 eV, respectively. These alloyed (ZnSe)(x)(CuInSe2)(1-x) and CuInSexS2-x nanocrystals with a broad tunable band gap have a high potential for photovoltaic and photocatalytic applications.