Eight fungicides used in soil treatments were assayed for their effect against three species of bacteria, two of actinomycetes, and three of fungi at intervals over a 32-week period. Methylmercury dicyandiamide (MMDD) was the only fungicide that showed some inhibitory effect at 1 ppm. MMDD and Hoe 2874 were the most effective fungicides followed by Chemagro B1843, thiram, and maneb in decreasing order of effectiveness. Captan with low solubility and two insoluble fungicides showed little or no activity. No fungicide at 1 or 10 ppm persisted for over 3 weeks. At 100 and 1000 ppm some fungicides persisted for periods extending beyond 32 weeks. The eight fungicides differed both quantitatively and qualitatively in their ability to inhibit or stimulate the various test organisms. The method is described and the effect of fungicides in soil treatment on the general microflora besides the soil pathogens is discussed.