Clinical reports on infections by pandrug-resistant (PDR) bacteria are scarce. This observational case series study was conducted during a 2-year period at a university hospital. Patients infected by PDR gram-negative bacteria comprised the study cohort. An isolate was defined as PDR if it was resistant to all antibiotic classes available for empirical treatment. A total of 21 patients infected by PDR gram-negative bacteria were recorded. The mean APACHE II score on admission was 18.8, the mean Charlson comorbidity index was 2.9, and 20 (95.2%) patients had a history of intensive care unit hospitalization. All patients had recent exposure to multiple antibiotics (median, 6 antibiotic groups). Infections occurred at a mean of 41.5 days after admission. The mean length of stay after infection was 54.6 days and 5 (23.8%) patients died due to the infection. Treatment was mainly based on a colistin-containing regimen (47.6%) or tigecycline (33.3%). All patients treated with tigecycline had total resolution of the infection and a notably shorter length of hospital stay after infection. In conclusion, PDR gram-negative bacterial infections are associated with considerable prolongation of hospitalization and mortality, although the mortality is not as high as that expected. Tigecycline appears to be effective for the successful treatment of PDR infections