question: The standard RT-PCR assay for COVID-19 is laborious and time-consuming, limiting the availability of testing. Rapid antigen-detection tests are faster and less expensive; however, the reliability of these tests must be validated before they can be used widely. The objective of this study was to determine the reliability of the PanbioTM COVID-19 Ag Rapid Test Device (PanbioRT) (Abbott) for SARS-CoV-2 in nasopharyngeal swab specimens. This was a prospective multicenter study in ten Spanish university hospitals of patients from hospital units with clinical symptoms or epidemiological criteria for COVID-19. Patients whose onset of symptoms or exposure was more than 7 days earlier were excluded. Two nasopharyngeal exudate samples were taken to perform the PanbioRT and a diagnostic RT-PCR test. Among the 958 patients studied, 359 (37.5%) were positive by RT-PCR and 325 (33.9%) were also positive by the PanbioRT. Agreement was 95.7% (kappa score: 0.90). All 34 false-negative PanbioRT results were in symptomatic patients, with 23.5% of them at 6-7 days since the onset of symptoms and 58.8% presenting CT >30 values for RT-PCR, indicating a low viral load. Overall sensitivity and specificity for the PanbioRT were 90.5% and 98.8%, respectively. The PanbioRT provides good clinical performance as a point-of-care test, with even more reliable results for patients with a shorter clinical course of the disease or a higher viral load. While this study has had a direct impact on the national diagnostic strategy for COVID-19 in Spain, the results must be interpreted based on the local epidemiological context.