Psoas abscess (PA) is an uncommon disease that has been increasingly reported in recent years. We reviewed patients with PA and analysed their clinical characteristics to improve the understanding of this rare disorder. The study retrospectively reviewed the clinical presentations, microbiology, and outcomes of patients with PA between 2011 and 2021 in Zhejiang Provincial People’s Hospital in China. There were 35 cases out of 23057427 hospitalised adult patients; the mean age was 60 years, and 65.7% of the patients were male. Primary symptoms were typically nonspecific. In all, 17 abscesses were considered secondary, and the most common aetiology was infective spondylitis. The most common causative organism for primary PA was Staphylococcus aureus, followed by Escherichia coli, while for secondary abscesses, there were multiple bacterial species. The overall in-hospital mortality rate was 6%. Secondary PA patients had longer hospital stays (mean, 23 vs. 28 days). PAs, as a serious infectious condition, usually present with nonspecific symptoms and laboratory test results, making early diagnosis difficult. The aetiological profiles differed from those reported in our study. Initial clinical status and subsequent imaging studies can lead to favourable outcomes.