Data concerning antibiotic therapy in italian ICUs are presented. These data were not directly measured: they have been derived from a previous study on costs of intensive care treatments. 78% of 1065 patients received antibiotic therapy. Empirical therapy was started in 82% of septic patients. 93% of septic patients had at least one antibiogram. In 96% of cases, 2 or more antibiotics were given. 85% of surgical non septic patients received antibiotic prophylaxis for an average of 3.6 days, with a 3rd generation cephalosporin in the majority of cases. 60% of medical non septic patients received antibiotic prophylaxis for an average of 6.2 days, mostly with a 3rd generation cephalosporin. These data raise doubts about the proper use of prophylaxis. These data can be considered a useful starting point for the development of a program of surveillance of infections in Italian ICUs.