Background Very few cases of Pneumocystis jirovecii pneumonia (PCP) have been reported in COVID-19 so far, mostly in patients with concomitant HIV infection or in solid organ transplant recipients. Despite COVID-19 is associated with lymphopenia and use of steroids, there are no studies specifically aimed to investigate risk factors for PCP in COVID-19 Methods retrospective case-control study in a cohort of patients with confirmed COVID-19. Direct immunofluorescence assay on respiratory samples was used to diagnose PCP. Results We enrolled 54 patients. Patients with PCP had significant lower median lymphocyte values (p=0.033), longer COVID-19 disease duration (p=0.014), higher cumulative dose of steroid received (p=0.026), higher CRP values (p=0.005) and lower SARS-CoV-2 vaccination rate than controls (p=0.029). Cumulative steroid dose (p=0.042) and the highest CRP value during the stay (p=0.012) were identified as risk factor for PCP, while SARS-CoV-2 vaccination with one (p=0.029) and two doses (p=0.049) as a protective factor for PCP, although not independently associated. Conclusions PCP develops in COVID-19 patients regardless of immunosuppressive conditions. However, a higher rate of PCP is significantly associated with the cumulative steroidal dose, high CRP values and lack of vaccination.