A 47-year-old type-2 diabetic male patient was hospitalized with diabetic foot infection, and piperacillin-tazobactam treatment was initiated. In the 3rd week of treatment, fever, malaise, myalgia, leukopenia, eosinophilia, and elevations of transaminases and acute phase reactants developed. Cultures remained sterile, and symptoms regressed with a change of medication and steroid administration. The clinical situation was accepted as “drug rash with eosinophilia and systemic symptoms” (DRESS) syndrome, which is discussed in detail.