Vertical movement of commercially formulated conidia ofBeauveria bassiana(Balsamo) Vuillimen was measured by recovery of colony-forming units (CFUs) at selected depths in four soil series after application of an aqueous suspension of conidia to soil surfaces. In greenhouse studies with soil blocks (40 by 20 by 20 cm) removed from field plots with a coring device, the number of CFUs recovered 72 h after application from depths below the surfaces was correlated (P= 0.0001) with water infiltration values of the respective soils. However, 95% of the total number of CFUs recovered in core samples of the Townley (29% sand, 32% clay, 39% silt), Greenville (64% sand, 28% clay, 8% silt), and Cecil series (59% sand, 22% clay, 19% silt) soils remained at the surfaces. In the Tifton series soil (87% sand, 5% clay, 8% silt), 87% of the total CFUs were recovered from the surface with an additional 9% recovered 4 cm below the surface. Core samples taken 2 h after application of an aqueous suspension of conidia to field plots also indicated that the four soils restricted vertical movement of the conidia. Greater than 94% of the total number of CFUs recovered in the cores were from the upper 5 cm of the profile of each soil series. At the 5–10 cm depth, 0.7, 1.8, 3.3, and 4.4% of the total CFUs were recovered from the Cecil, Greenville, Tifton, and Townley series soils, respectively. Only small percentages of total CFUs were recovered from the 10–15 cm profile of each soil. Retention of conidia in the upper profile of these soils appears to be caused by mechanical filtration within the soil structure.