Current and detailed knowledge of antibiotic use is essential in order to implement strategies for reducing the overuse of antibiotics. The objective of our study was to determine the effectiveness of the implementation of the hospital antibiotic policy (HAP) by assessing antibiotic consumption in the Special Neonatal Care Unit (SNCU) in Warsaw, Poland, before and after this intervention. Antibiotic use was calculated in daily defined doses (DDDs) per 100 patient-days and DDDs per 100 admissions. The antibiotics were ranked by volume of DDDs and the number of antibiotics, which accounted for 90 % and 100 % of the total volume, respectively: DU90% and DU100% (where DU stands for drug use). Total antibiotic consumption increased slightly after the introduction of the HAP: the total DDDS was 707.87 and 753.12 in 2011 and 2012, while the number of DDDs/100 admissions was 352.17 and 369.12 in 2011 and 2012, respectively. After the introduction of the HAP, an increase in ampicillin and aminoglycoside use was observed, along with a reduction in the DU100% and DU90% rates (15 vs. 9 and 4 vs. 3, respectively). The introduction of the HAP resulted in changes in antibiotic consumption patterns, but the general antibiotic consumption density remained the same.