The main objective of this study was evaluation of activity coefficient of FS2 fotosystem (ACFS2) in different maize genotypes contrasted by drought stress tolerance. Recording of ACFS2 was performed with portable chlorophyll fluorimeter PM2100, under maize seedlings at the stage of three leafs, grown in normal and stressed conditions. Inbreeds and hybrids with a different drought reaction in the field were used. Significant differences among all genotypes were found for ACFS2 in both stressed and not stressed seedlings. Based on obtained results all analyzed genotypes were shared in several groups with different drought stress tolerance. This group division fit well with the results obtained from germination in osmotic solutions, evaluation of membrane thermo stability and field observation. In conclusion ACFS2 could be used as a drought tolerance trait in maize.