Eucharistic Miracle of Tixtla

Host exuded a reddish substance during Communion distribution on October 21, 2006. Scientific analysis (2009–2013) found AB human blood, myocardial tissue with signs of active repair, and no natural explanation for the substance's origin from inside the Host.

On October 21, 2006, during an annual parish spiritual retreat at the Church of St. Martin of Tours in Tixtla de Guerrero, Guerrero, Mexico, a consecrated Host began to exude a reddish substance during the distribution of Holy Communion. A religious sister serving as an extraordinary minister of Holy Communion noticed the substance in her ciborium and alerted the presiding priest, Fr. Leopoldo Roque, who immediately notified Bishop Alejo Zavala Castro of the Diocese of Chilpancingo-Chilapa.

Bishop Zavala Castro established a theological commission to investigate the event. In October 2009, he commissioned a formal scientific research program under Dr. Ricardo Castañón Gómez, a Bolivian clinical neuropsychophysiologist who had led the scientific investigation of the Buenos Aires Eucharistic miracle in 1996. Analysis continued until approximately 2013, with findings presented at an International Symposium in Chilpancingo on May 25, 2013.

The laboratories involved — based in Bolivia, Guatemala, Mexico, and the United States — independently reached convergent findings. The substance was confirmed to be human blood of type AB, containing hemoglobin, white blood cells, red blood cells, and active macrophages. Histopathological analysis identified the tissue as myocardium — cardiac muscle — with striated cardiac cells showing signs of active repair consistent with living tissue under stress. Two independent forensic analyses confirmed the substance originated from the interior of the Host rather than external contact. Attempts to sequence DNA recovered from the tissue were unsuccessful, an anomaly consistent with findings from the Buenos Aires investigation.

Tixtla joins Buenos Aires (1996) and Lanciano (eighth century) in independently producing AB blood and stressed left-ventricular cardiac muscle tissue — a convergence that investigators have noted but that remains outside the scope of the Church's formal declarations.

On October 12, 2013, Bishop Zavala Castro issued a Pastoral Letter declaring the event "a Divine Sign" with "no natural explanation" and explicitly excluding paranormal origin. He stated it was "a marvelous sign of the love of God that confirms the Real Presence of Jesus in the Eucharist."

The diocesan process has not received Vatican-level elevation. Bishop Zavala Castro's successor, Bishop Salvador Rangel Mendoza, has stated publicly that the Vatican designated the event a "Eucharistic phenomenon" — not formally a miracle in the canonical sense — and that the diocesan process has not been concluded. A canonical miracle declaration requires papal recognition; the local bishop's declaration is the current standing.