Eight-hundred and thirty three (833) samples of biological prod­ucts ("31 5" live attenuated egg adapted vaccines, "1 93" live attenuat­ed tissue culture adapted vaccines, "268" inactivated vaccines, "12" an­tigens, "9" anti-tetanic serum, 11 normal serum (neoborn calf serum, fetal calf serum, horse and swine serum and "25" physiological saline) were screened against common contaminants (Bacterial, Fungal and My­coplasmal), and antibiotic sensitivity to these contaminants were deter­mined. The results revealed that, out of the total number of samples (833), 18 samples (2.2%) were contaminated with various types of con­taminants (anthracoid "6", proteus "5", fungus "2", staphylococci 2, E.coli1, Mycoplasma 1 and streptococci 1). Concerning the results of an­tibiotic sensitivity test, it was clear that anthracoid, proteus, fungi, E.coli and Mycoplasma were sensitive to chloramphenicol, P-nitrophenyl glyce­rol, mycostatine, amoxycillin, and lincospectin, respectively, with varying degrees. Staphylococci and streptococci contaminants were sensitive to benzyl penicillin. By application of this study, it is possible to control the contaminants which interfere the production of different veterinary bio­logics.