The performance of various air-cleaning devices and an assembled air cleaner has been evaluated for the removal of biological pollutants in indoor air. Bacteria, fungi, and viruses were sprayed in a test chamber, and air samples in the chamber were taken for analysis. Air-cleaning devices - UV lamp, ion generator, an UV LED and plasma electricity dust collector - were tested for their ability in the removal of microorganisms in the air. The UV lamp and the ion generator tested exhbited complete sterilization effect within 4hrs of operation. Other devices were less effective: The extent of removal by the UV LED and the plasma electricity dust collector after 6hrs of operation was about 20% to 82%, depending on the microorganisms tested. The performance of an assembled air cleaner was much superior to individual air-cleaning devices: the extent of removal being 97.6%, 99.1%, 98.7%, and 93.7% for Staphylococcus aureus (Gram(+) bacteria), Escherichia coli (Gram(-) bacteria), Aspergillus niger and Penicillium funiculosum (fungi), respectively, after 3hrs of operation. The removal of influenza virus was even more effective, with 99.9% of removal within 25min of operation. The results show that the air cleaner is effective for the removal of microbial and viral pathogens in the air.