BACKGROUND: Catheters are extensively used for coronary angiographies. These devices are long, thin, and flexible tubes of variable diameters that are made of the following polymer compounds: polyamide, polyurethane and Teflon. The objectives of this study are to identify changes that occur in the polymeric structure of the catheters, including an analysis of microcracks, fissures, cuts, perforations, roughness, and porosity in the internal and external layers after the first, second, third, and seventh reprocessing. METHODS: Five catheters of the same brand and manufacturer were selected for each analysis, except for the new and seventh catheters, which had only one sample. The catheters that we analyzed included new catheters, catheter reprocessed once (1st), catheters reprocessed twice (2nd), catheters reprocessed three times (3rd), and catheters reprocessed up to seven times (7th). Samples were cut into small pieces and the scanning electron microscope and infrared spectroscopy were used for analysis. RESULTS: Scanning electron microscopy (SEM) of reprocessed catheters revealed rougher surface with porosity, stainless steel wires, peeling of the inner layers, micropores, small holes, disordered cracks, cracks, grooves, microcracks, granular appearance, dots whitish, diffuse microcracks, desquamation, diffuse recesses, depressions, protrusions and deep crevices. Infrared spectroscopy suggested a possible change in the chemical structures of the polymer. There was a directly proportional relationship between the reprocessing number and the carbonyl ratio. CONCLUSIONS: The combined SEM and infrared analyses reveal that reprocessing damages the integrity of coronary angiography catheters. Therefore, the reprocessing of such catheters is not recommended.