The genetics of the absence of heterosis in hybrid plants involving lines TS11 and P22 was studied. Segregation of hybrids (TS11 x 092) x P22, (TS11 x A619) x P22, and (TS11 x 19-3-3) x P22 for plant height was analyzed. The distribution pattern was compared with that of hybrid TS11 x P22, in which hybrid vigor was not observed or was minimal. It was shown that, in 1993 and 1996, the absence of heterosis in hybrid plants was controlled by two recessive genes. In 1998, only one gene was identified. It was suggested that lines TS11, P22, and ST156 may be used to identify genes that determine heterosis in maize.