Argentina · 20th Century
Buenos Aires
On August 18, 1996, at the Church of Santa María y Caballito Almagro in Buenos Aires, a consecrated Host fell during Communion distribution. Following proper protocol, Fr. Alejandro Pezet placed it in water in the tabernacle to dissolve. Eight days later, Fr. Pezet found that the Host had not dissolved but appeared to have developed what looked like bloody tissue. He immediately photographed the phenomenon and reported it to then-Auxiliary Bishop Jorge Mario Bergoglio.
About this miracle
Bishop Bergoglio—who would later become Archbishop (1998-2013) and Pope Francis in 2013—ordered the Host to be preserved and photographed, establishing a chain of custody for the scientific investigation that followed. Bergoglio, as auxiliary bishop and later archbishop, authorized the investigation and permitted local veneration; he was associated with the case through his years in Buenos Aires until his 2013 election.
Between 1999 and 2005, under Bergoglio's authorization, tissue samples were sent to laboratories worldwide. Dr. Frederick Zugibe, former Chief Medical Examiner of Rockland County, performed a blind analysis—unaware of the tissue's origin. He reported what appeared to be heart muscle (left ventricle) with white blood cells suggesting the tissue was alive when sampled. Serological testing reported blood type AB, also reported for the Shroud of Turin. (The 'blind test' framing is disputed, and forensic critics caution that AB typing here cannot establish a single human source.)
This Buenos Aires phenomenon is part of a reported pattern. Across several modern alleged Eucharistic miracles—Buenos Aires, Sokółka, Legnica, and Tixtla—investigators have reported finding what appeared to be human cardiac tissue with signs of agony and trauma. Some also report blood type AB. For believers, this consistency is seen as significant; for skeptics, it may raise questions about methodology or suggest alternative explanations. The Church's discernment considers multiple factors beyond scientific data alone.
This phenomenon profoundly impacted Bergoglio's future papacy. His emphasis on mercy, encounter, and accompanying those on the peripheries was deepened by this experience of investigating an apparent sign of Christ's enduring presence even when the Host was accidentally discarded. For those who accept its authenticity, the Buenos Aires phenomenon speaks powerfully of Divine Mercy: a visible sign interpreted by believers as Christ's Sacred Heart remaining present to our skeptical age.