The authors made plant pathological investigations of 10 cultivated grass species and cultivars from September 2004 to June 2007. The aim was to determine species diversity and dominance relations of rust diseases of grasses. Four rust species (Puccinia recondita, P. graminis, P. coronata, P. striiformis) were determined on grasses, from among which crown rust (P. coronata), leaf rust (P. recondita) and their forma specialis caused higher infection. The first significant rust infection of grasses was observed on turion after harvesting at the end of July. The maximum value of rust fungi infection was determined in September. This work gives information on rust fungi incidence on cultivated grass species and discusses the curve of seasonal epidemic caused by Puccinia species.