This research sought to compare the microbiological status of pumice slurry in clinical and nonclinical dental laboratories. Samples were inoculated onto selective and nonse lective media. Resultant colonies were counted and identified to genus or species level. In the nonclinical laboratory, counts were constant at approximately 10 to the seventh power to 10 to the eighth power cfu/g. Pseudomonad s, staphylococci and Bacillus spp comprised the major pumice contaminants in both laboratories. It was concluded that nonclinical laboratories are not immune from the presence of potentially pathogenic microorganisms in pumice slurry. Disinfectant reduces contamination by oral microorganisms.