In this study, soil cadmium fractions and their relationships with some microbiological properties were investigated in disturbed twenty soil samples (agricultural area) of Bafra plain in Turkey. Total Cd in the 20 soil samples under study ranged from 1.83 to 2.73 v µg - g m 1 with an average of 2.32 v µg - g m 1. A sequential fractionation showed that 7.3-"18.5% of total Cd was exchangeable (EX-Cd), 4.1-10.8% was organically complexed (OM-Cd), 6.1-7.6% was associated with Mn oxides (MnO-Cd), 5.2-8.7% was associated with amorphous iron oxides (AFeO-Cd) and 5.8-7.2% was associated with crystalline iron oxides (CFeO-Cd). Most of the total Cd was present in residual (R-Cd) form (54.0-62.1%). In the study, dehyrdogenase activity, catalase activity, urease activity, CO 2 production and microbial biomass-C were approximately 205.3 v µg TPF/1 v g dry soil, 18.5 v ml O 2 /5 v g dry soil, 148.7 v µg N/1 v g dry soil, 14.7 v mg CO 2 /100 v g dry soil, 58.5 v mg C/100 v g dry soil in researched soils. Soil organic carbon contents gave the significant positive correlations with microbiological properties at p 0.01. Microbiological properties of soil samples are affected negatively by EX-Cd and AFeO-Cd rather than the other Cd fractions. © 2002, Copyright Taylor & Francis Group, LLC.