In this study, different types of indoor environments (primary school, kindergarten, cafeteria, restaurant, dormitory, dwelling, off-ice, sport salon, library, classroom, and laboratory) and their outdoor environments were investigated in terms of bioaerosol contamination. A total of 120 environments were investigated in Ankara, Turkey. The single-stage Andersen sampler was used for viable bioaerosol sampling. During the sampling, indoor and outdoor temperature, relative humidity, and CO2 concentration were measured. Total bacteria counts (TBC) and fungi concentrations varied on a large scale with in and be tween the sampling site groups (10 - 10(3) CFU/m(3)). The highest TBC levels were measured in kindergartens, primary schools, restaurants, high schools, and homes, while the highest mold levels were measured in kitchens, bathrooms, and offices. Micrococcus spp., Staphylococcus auricularis, and Bacillus spp. were predominant bacteria species and Penicillium spp., Aspergillus spp., and Gladosporium spp. were the most observed mold genera detected in the samples. Indoor-to-outdoor (I/O) ratios of the observed fungi counts were calculated as approximately around 1, and for bacteria counts these ratios were higher than 1. There was no statistical difference between indoor and outdoor mold levels, while a significant difference was found between indoor and outdoor bacteria levels (p < 0.001). A significant correlation between indoor CO2 and bioaerosols indicates insufficient ventilation.