Objectives: The aim of the study was to determine the percentage of positive skin tests to cephalosporins and fluoroquinolones, and to determine the relationship between results with the severity of the previous reaction, time interval from reaction to testing, hypersensitivity to penicillins and other allergens, age and sex of patients and anamnestic data on hypersensitivity to these groups of antibiotics. Study design: The study is a cross-sectional study with historical data. Subjects and methods: Subjects of this study were all patients who underwent hypersensitivity testing to cephalosporin and fluoroquinolone antibiotics, by skin tests and exposure, in Clinical Pharmacology outpatient clinic at the Clinic for Internal Diseases as a part of Clinical Hospital Center in Osijek, in the period from the beginning of October 2016 to the end of April 2021. Data on 49 subjects was collected from archival medical records, and it contained demographic data, data on comorbidities and other drugs taken by patients, data on allergic reactions, the existence of allergies to other groups of drugs and other allergens, hypersensitivity testing method (skin test, exposure), test outcome, and recommendations given to the patient. Results: Cephalosporin hypersensitivity was found in 8 % of patients, and fluoroquinolone hypersensitivity was found in 18 %, by intradermal and drug challenge. Intradermal tests are reliable in diagnosing hypersensitivity. A higher incidence of hypersensitivity was observed in women, patients aged 31 to 55 years, and allergic to penicillins. Cephalosporins more often cause type I reactions, and fluoroquinolones type IV. No correlation was found between the test outcome with the severity of the primary reaction, angioedema, the time interval from the reaction to testing, the existence of hypersensitivity to other allergens and anamnestic data on hypersensitivity. Conclusion: Intradermal tests are reliable in diagnosing hypersensitivity, while prick tests are not. 10 % of the subjects were found to be hypersensitive, while the other 90 % were allowed to use the tested antibiotics in the future.