Biofilm formation on milk equipment is a well-known phenomenon and it has caused pollution, safety hazards and substantial economic loss. This study was undertaken to examine the efficacy of the sanitizers including iodophore, quaternary ammonium compounds and calcium hypochlorite against total mesophilic count (TMC), total psychrophilic count (TPC), total thermoduric count (TTC) and total coliform count MPN/ ml of the examined raw milk samples. Additionally the sanitizers were also tested against Escherichia coli strains isolated from the examined milk samples. The result shows that psychotrophic bacteria were more resistant on sanitizer used than thermoduric bacteria. Among the three commercially sanitizer tested, quaternary ammonium compound was the most potent against microorganisms after 20 min exposure time using warm water. However, calcium hypochlorite and iodophore showed a lower effect on the bacterial groups. The resistance of Escherichia coli strains to the sanitizer was strain dependent.  It was concluded that the resistances of microbes to different sanitizers should be taken into account when planning the cleaning of milking equipment.