Damping-off, caused by Rhizoctonia solani and Pythium ultimum, is a very important plant disease and affectsseeds and seedlings of many plant species worldwide. To investigate control efficacy of Serenade formulation(1.34%, SC) against Rhizoctonia and Pythium damping-off diseases, seeds of chili pepper and cucumber weresown in soils inoculated with R. solani and P. ultimum and Serenade formulation was applied by soil-drenching with9-, 19-, and 39-fold dilutions. Control values of Serenade formulation on Rhizoctonia damping-off of chili pepperwas 58% and 29% for 9- and 19-fold dilutions, respectively. In the case of cucumber Rhizoctonia damping-off,Serenade treatments showed similar control efficacy with damping-off of chili pepper. On the other hand, controlefficacy of Serenade formulation on Pythium damping-off of cucumber was less than control effects onRhizoctonia damping-off. Only Pythium damping-off of chili pepper treated with 9-fold dilution Serenadewas statistically different with untreated control. This result suggest that Serenade formulation could be effectivelyused for controlling Rhizoctonia and Pythium damping-off diseases.