Reducing potentially inappropriate medications (PIMs) is a challenge in post-acute care hospitals. Some PIMs may be associated with patient characteristics and it may be useful to focus on frequent PIMs. This study aimed to identify characteristic features of PIMs by grouping patients as in everyday clinical practice. A retrospective review of medical records was conducted for 541 patients aged 75 years or older in a Japanese post-acute and secondary care hospital. PIMs on admission were identified using the Screening Tool for Older Person’s Appropriate Prescriptions for Japanese. The patients were divided into four groups based on their primary disease and reason for hospitalization: post-acute orthopedics, post-acute neurological disorders, post-acute others, and subacute. Approximately 60.8% of the patients were taking PIMs, with no significant difference among the four patient groups in terms of prevalence of PIMs (p = 0.08). However, characteristic features of PIM types were observed in each patient group. Hypnotics and nonsteroidal anti-inflammatory drugs were common in the post-acute orthopedics group, multiple antithrombotic agents in the post-acute neurological disorders group, diuretics in the post-acute others group, and hypnotics and diuretics in the subacute group. Grouping patients in clinical practice revealed characteristic features of PIM types in each group.© 2023. Springer Nature Limited.