Background: Pneumocystis pneumonia (PCP) is well-described in younger and HIV-infected populations, but limited data are available for older non-HIV-infected patients. The aim was to describe the clinical characteristics, management and outcomes of PCP in older non-HIV-infected patients and to identify factors associated with in-hospital mortality. Methods: This multicentre, retrospective, cohort study included patients aged ≥ 75 years, hospitalised for non-HIV-related PCP in 12 French university hospitals between January, 2010 and December, 2021. PCP diagnosis was confirmed by PCR or microscopy. Data on demographics, comorbidities, clinical features, management and outcomes were collected. Factors associated with in-hospital mortality were identified by univariate and multivariate analysis. Results: A total of 175 patients were screened and 162 were included (median age: 79 years, 57.4% male). Most patients had haematological malignancies (35.8%) or solid tumours (34.5%) and were treated with long-term corticosteroids (60%). Respiratory symptoms (87.6%) and bilateral interstitial lung involvement were common. Diagnosis was based on PCR of bronchoalveolar lavage (66.4%) or sputum samples (32.3%). In-hospital mortality was 27.8%. CRP level > 110 mg/L (HR = 2.55 [95%CI: 1.35–4.83], p = 0.004) and initiation of corticosteroids for PCP treatment (HR = 1.89 [95%CI: 1.03–3.44], p = 0.039) were associated with mortality. Patients with higher oxygen saturation at admission (HR = 0.94 [95%CI: 0.91–0.97], p < 0.001) had a lower risk of death. Conclusion: PCP in older non-HIV-infected patients has a high mortality rate, particularly in the presence of elevated CRP, hypoxaemia or corticosteroid use. Future research should focus on identifying subgroups potentially benefiting from corticosteroids and exploring safe therapeutic options for this vulnerable population