Extracellular lipases and proteases are produced by most microorganisms under suitable conditions. Storage of milk for long periods at refrigeration temperatures has resulted in new quality problems for dairy industry. These problems are related to growth and metabolic activities of microorganisms at low and high temperatures. These microorganisms are common contaminants of milk (Cousin, 1982). Thermophiles and psychrotrophs are an important group of microorganisms in milk because they cause spoilage by biochemically altering the constituents of milk. The two most important reactions of interest in the milk products are proteolysis and lipolysis. In this study the incidence of thermophilic and psychrotrophic Bacillus species, and comparison of their proteolytic acitivites in milk samples were undertaken for evaluation.