ObjectivesTo evaluate the incidence and types of drug-related problems (DRP) in a general teaching hospital and to evaluate the acceptability of pharmaceutical interventions by the medical team.DesignProspective cohort study during 2 years.SettingConducted in a Brazilian University Hospital.ParticipantsThe patient cohort consisted of 9303 patients with a total of 12 286 hospitalisation episodes.Primary outcome measuresDRP detected by pharmacists’ review of 100% medication orders using Pharmaceutical Care Network Europe 6.2 classification.ResultsPatients with a mean age of 52.6±17.7 years and 50.9% females. A total of 3373 DRP in 1903 hospital episodes were identified, corresponding to a cumulative incidence of 15.5%. ‘Treatment ineffectiveness’ (11.5%) and ‘Treatment costs’ (5.90%) were the most common DRP and ‘Drug use process’ (18.4%) and ‘Treatment duration’ (31.0%) the main causes of DRP. The medicines involved most often involved in DRP were anti-infectives (36.0%), mainly cephalosporins (20.2%), antiulcer (38.6%), analgesics/antipyretics (61.2%), propulsives (51.2%), opioids (38.5%) and antiemetics (57.4%). From 1939 pharmaceutical interventions, at least, 21.4% were not approved by the medical team.ConclusionDRP detected by 100% medication order review by hospital pharmacists occur in a significant proportion of hospital episodes, the most frequent being related to treatment effectiveness and treatment costs. The medications mostly involved were cephalosporins, penicillins, antidyspeptics, analgesics, antipyretics, opioids and antiemetics. Pharmaceutical interventions had low acceptability by the medical staff.