The use of antibiotics in the course of one year (1 September, 2006 until -31 August, 2007) was evaluated in 23 pig farms housing about 18 000 animals in one district in Northrhine-Westfalia. The veterinary application and dispensary documents ( 13 TAHAV) as well as respecting farmers' documents (ANTHV) served as data sources. Based on this data the amount of the used free substances, the number of treatment units as well as the therapy frequency were evaluated for each age group. Treatment frequency describes the average number of treatment days with one substance in a certain timeframe for a particular age group With the treatment frequency comparisons of antibiotic use can be made regardless of population size. It was shown in this study that piglets (suckling piglets) received about 6.1 antibiotic units per 100 days, fattening pigs about 4.6 units and sows 0.9 units per 100 days. All in all about 676 kg of free antibiotic substances were applied to the animals, especially tetracyclines (58%), sulfonamides/trimethoprim (16%), macrolides (13%) and beta-lactams (11%). These consumption figures do not reflect, however, the frequency of use in animal therapy. 34.7% of all applications performed in pigs were with makrolides, as opposed to only 25.1% with tetracyclines. This discrepancy in consumption levels when compared to the number of treatment units is due to the different dosages applied. With respect to the largest amount of drugs applied, these were used in the treatment of respiratory infections. But, most of the pigs were treated for skin disease.