Salmonella rods belong to the most widespread microorganims in the environment. Their role as a toxico-infection factor is significant and it is related to the common occurence in poultry. That is why an important role in the transmission of the microbe is played by poulrty. To limit the losses caused by Salmonella it is necessary first of all to identify the infection factor as quickly as possible and introduce effective control of products of poultry origin throughout the production cycle. The pupose of the studies was to determine the effect selected antibiotics on the results of serological tests in the case birds naturally infected by Salmonella rods and in experimental conditions. The studies were conducted on birds from two farms in the vicinity of Lublin. They were infected both naturally and experimentally. The following antibiotics were used in the experiment: amoxyciciclin with clavulanic acid (Amoksiklaw, Lek Polska), spiramicin with kolistin (Spiracol, Grodziskie Zakłady Farmaceutyczne), linkomycin with spectiomycin (Lincospectin, Elanco), enrofloxacin (Enrocin, Grodziskie Zakłady Farmaceutyczne), norfloxacin (Nortil, Bremmer Farma), tiamphenicol (Tirsan, Fatro), flophenicol (Nuflor, Schering-Plough Animal Health). The results of serological tests obtained in the group of experimentally infected chicken point out that the applied antibiotic therapy significantly reduced the level of antibodies, which was reflected in the low percentage of positive results achieved in ELISA test and agglutination method. In the case of naturally infected birds the ob.btained values showed that the antibiotic therapy had a significantly smaller influence on the level of antibodies and this influence was limited only to some antibiotics (norfloxacin, enrofloxacin, chloramphenicol).