The aim of this paper was to assess the microbiologic quality of air in broiler houses. The number of bacteria (mesophile, staphylococci, streptococci and gram-negatives) and fungi was determined in 6 broiler houses with chicken of different ages (1-6 weeks old) through specific methods. The results were statistically processed by using the SPSS software, version 17. The number of bacteria and fungi varied in the 6 broiler houses, ranging from 2.25 x 105 to 2.17 x 106 for the total number of mesophilic bacteria, between 3.5 x 104 – 1.27 x 106 for staphylococci, 7.4 x 104 – 5.01 x 105 for streptococci, 3.5 x 103 – 1.53 x 104 for gram-negatives and from 1.67 x 104 to 8.13 x 104 for fungi, respectively. The number of bacteria and fungi were significantly lower for the younger chicken (p < 0.05). The proportions of groups with hygienic significance within the total mesophilic bacteria number were: 15.7% - 68.6% staphylococci, 6.7% - 45.6% streptococci and 0.2% - 4.5% gram-negatives. The comparative appraisal of the microbiologic quality in the broiler houses showed better air quality in the youngest chicken’s house (one week of age). The obtained results indicate the necessity for increased ventilation and for air disinfection during the chicken’s fattening period.