Aim To examine discharges of octogenarians, nonagenarians and centenarians from Portuguese public hospitals, namely admission type, principal diagnoses, comorbidities and length of stay. Methods The present study used administrative data from public acute care hospitals in the Portuguese National Health Service. All discharges of persons aged ≥80 years between 2000 and 2014 were analyzed. HCUP Clinical Classifications Software was considered to aggregate principal diagnosis, and comorbidities were assessed using the Charlson Comorbidity Index computed using International Classification of Diseases 9th Revision Clinical Modification codes. Results A total of 2 494 924 discharges of persons aged 80 years or older were registered. Most (73.7%) referred to inpatient episodes, of which 73% were unplanned and medical (non‐surgical). Pneumonia (12.2%), acute cerebrovascular disease (7.1%) and non‐hypertensive cardiac heart failure (5.3%) were the most common principal diagnoses among inpatient episodes. Congestive heart failure and diabetes without chronic complications were the two most frequent comorbidities (16.6%), and discharge diagnoses with higher median length of stay were tuberculosis, burns, and infective arthritis and osteomyelitis. Conclusions The number of hospitalizations of the oldest old has suffered a significant increase in the past few years, reinforcing the need for healthcare services being prepared to the specificities of the oldest old population. Geriatr Gerontol Int 2017; ••: ••–••.