The present study was conducted in a large mechanical city bakery. The AS-50 aspirators equipped with cellulose membrane filters were used for dust sampling. Airborne microbial content was assessed by means of sedimentation and aspiration using an Andersen sampler on Petri plates containing McConkey's medium. The following Gram-negative rods were detected in the bakery atmosphere: Erwinia herbicola, Acinetobacter Lwoffi and Klebsiella oxytoca, in concentrations ranging from 1.4 10(4) to 3.5 10(5) colony forming units per cubic meter (cfu/m3). Endotoxin concentration in flour dust sampled in selected work areas of the bakery ranged from 6.7 micrograms of endotoxin per gram of dust (micrograms/g) to 20.3 micrograms/g. Endotoxin level in the air was 0.04-0.05 micrograms of endotoxin per cubic meter (micrograms/m3). The results of our show that aspiration sampling is necessary for evaluation of airborne bacterial content and demonstrate the efficacy of the Limulus test of varying sensitivity to assay endotoxin level in the airborne dust. The advantage of this method is the possibility of assessing endotoxin in crude dust extracts.