A comparison was made of herbicide tolerance results for two years, one dry (2003) and one wet (2004). The maximum permitted dose and twice this rate of the herbicides (mesotrione, mesotrione + atrazine, nicosulfuron, rimsulfuron) were sprayed on inbred maize lines in the 7-8-leaf stage. The effect of the herbicides on 20 inbred lines was evaluated on the basis of visible phytotoxic symptoms. In the dry year the greatest damage, averaged over the inbred lines, was caused by the double rate of rimsulfuron and nicosulfuron, but the plants had overcome this by the end of the vegetation period. In 2004 the cool wet spring weather retarded the metabolic processes of maize, leading to greater phytotoxic damage. The most severe symptoms were observed for the double rate of mesotrione +atrazine. The phytotoxic damage caused by the “normal” rates applied in commercial maize production was overcome by the lines in the wet year, too. Despite the initial visible phytotoxic damage, none of the herbicides caused significant differences in grain yield between the control and the single or double rates of treatment.