In our study, effects of fungicides mancozeb and dinocap on C and N mineralization were measured in arable and grassland soil. The soils were treated with these fungicides at the application and 10 times lower doses and then incubated at 20 degrees C for 2 weeks. Carbon mineralization (basal and substrate-induced respiration) and nitrogen mineralization (potential ammonification and nitrification) were evaluated 1 and 14 days after the treatment. After 14 days, ammonification was decreased to 48% and 83% at dinocap application dose in arable and grassland soil, respectively. Application dose of mancozeb caused significant decrease of nitrification to 11.2% and 5.6% in arable and grassland soil, respectively. Basal respiration and substrate-induced growth were rather stimulated by fungicides, especially at lower application doses. To conclude, potential risk may exist to soil microorganisms and their activities in soils treated routinely by mancozeb or dinocap.