ABSTRACT BACKGROUND: Cell phones have become indispensable for professional activities, including healthcare. Thus, they are possible sources of bacterial contamination. There is a scarcity of data in the literature regarding identification of risk factors for contamination of cell phones with pathogenic bacteria. OBJECTIVE: To compare the prevalence rates of Staphylococcus aureus (S. aureus), methicillin-resistant S. aureus (MRSA) and/or Enterobacteriaceae on cell phones belonging to hospital healthcare staff and university students in Curitiba, Paraná, Brazil, and to identify variables associated with such contamination. DESIGN AND SETTING: Cross-sectional study conducted in a public university’s referral hospital and lecture buildings in 2017. METHODS: We sampled the surface of cell phones using the dipslide method, with Baird-Parker agar and Escherichia coli-coliform chromogenic (ECC) agar. We assessed the population’s sociodemographic, behavioral and hygiene characteristics through interviews. Possible presence of S. aureus colonies was confirmed using agglutination tests, with evaluation of methicillin sensitivity. Colonies in ECC medium were counted. Stepwise logistic regression (forward P < 0.15) was performed to identify characteristics associated with bacterial contamination. RESULTS: The prevalence rates of S. aureus, MRSA and Enterobacteriaceae were, respectively, 32%, 4% and 3%. No difference was found between the hospital and university-based populations (P > 0.05). The only variable associated with bacterial contamination was the use of cloth/velvet/leather phone cases (odds ratio: 2.92; 95% confidence interval: 1.08-7.91). CONCLUSIONS: Potentially pathogenic bacteria were prevalent on the cell phones of this hospital and university population. Use of phone cases made of cloth-like material should be discouraged, especially in hospital settings.