The aim of the study was to determine the biodiversity of flies (Diptera) occurring in livestock buildings and in their direct proximity, in various systems of ruminants rearing. Flies were collected by net sweeping during the summer, in two cowsheds (one large-scale, and one traditional farm), and one specialist sheepfold, located in the Lesser Poland region of Poland. The insects were captured – both inside and outside the premises – three times (at 10:00, 12:00 and 14:00) on selected warm and sunny days of June, July and September, when animals were assumed to be the most harassed. A total of 18365 flies belonging to 13 families were obtained. The largest relative abundance of Diptera were from the Drosophilidae family (61.4%), and dominating Muscidae species – Musca domestica L., 1758 (19.2%) and Stomoxys calcitrans (L., 1758) (5.7%). More than half (55.5%) of all flies were captured in the morning, and their vast majority not inside a livestock building (28.2%), but in its close proximity (71.8%). This was particularly true of the large-scale cattle farm. The smallest number of insects, although with the highest biodiversity, were collected at the sheepfold. Regardless of their particular animal preferences, the insect species found were commonly occurring in different livestock sectors.