A cross-sectional study was conducted to evaluate the effectiveness of manual and automated dialyzer reprocessing. Dialyzers were filled with fluid thioglycollate medium from blood and dialysate chambers after being reprocessed and chemically sterilized with 0.2% peracetic acid. They were incubated for 14 days at 35°C ± 2°C, and microbiologic analysis was performed. Microorganisms were identified in 3 of the 11 samples (27.3%) from the blood chambers: Sphingomonas paucimobilis (2/3) and Penicillium spp (1/3) and in 11 of the 11 samples (100%) from the dialysate chambers: S paucimobilis (7/11), Stenotrophomonas maltophilia (4/11), Pseudomonas aeruginosa (3/11), Candida spp (1/11), and Acinetobacter baumannii (1/11). Of the 4 manually reprocessed dialyzers, gram-positive bacillus were identified in 1 sample (25%) from the blood chamber, and Bacillus spp and Burkholderia spp were identified in 1 sample (25%) from the dialysate chamber. The dialyzers reprocessing can pose risks safety because of exposure patient to microorganisms.