The paper presents results of studies on the occurrence and economic importance of maize diseases: common smut (Ustilago zeae/Beckm./Unger) root et stalk rot (Fusarium spp.) and eye spot of leaves (Kabatiella zeae Narita et Hiratsuka) (conducted in 1993-1999) as well as corn rust (Puccinia sorghi Schw.) and blotch of leaf sheaths (Pseudomonas andropogoni E. F. Smith/Stapp., P. syringae van Hall.) (conducted in 1996-1999).