We analyzed the impact on antimicrobial consumption of antimicrobial therapy totally guided by an infectious disease specialist (iD). in a teaching hospital antibiotic consumption was recorded yearly from 1998 to 2005 in three units. Antibiotic policy was introduced in 1999. in Unit A, restricted antimicrobials were prescribed after approval by the head of the unit. the iD was involved as a consultant upon request. in unit b, restricted antimicrobials were approved by an iD. All other antimicrobials were prescribed by the physicians on the ward. in unit C, all antimicrobials were prescribed by an iD. A significant decreasing trend in antibiotic consumption in defined daily doses (DDD) per patient day and per admission, and cost of antimicrobials per patient was observed in unit C, a decreasing trend in antibiotic consumption per patient was observed in unit b as well. totally iD guided antimicrobial therapy is an efficient method of antimicrobial policy.