Recently, downy mildew of maize caused by Peronosclerospora sorghi causes serious losses in maize seed production in Egypt. The downy mildew incitant was detected in seed samples in a various range of infection levels. The obtained results suggest that approxemitely 60% of the infected maize seeds will give rise to infected plants when mature. The correlation of seed infection level /disease development was eight / five. Seed dressing decreased disease seed transmission by about 75%. Fungicidal seed treatment when applied by the solvent infusion method resulted in satisfactory control and reduced disease to about 10% .