Ingrassias is supposed to have been born in Recabuto near Palermo. He studied medicine at Padua, and received his doctorate in 1537. His ability gained for him an enviable reputation, and he was called to the chair of medicine in Naples. There his lectures on medicine and anatomy were soon attended by crowds of students, and his skill in practice gained for him the title of the Sicilian Hippocrates. In 1560, he left Naples and returned to Palermo, and three years later Philip II, King of Spain, made him physician in chief to Sicily and the adjacent islands. When the plague ravaged the countryside, he rendered great service and was granted a pension, which he refused to accept, an action so unusual that it was recorded in the accounts of his life.
His name has been given by anatomists to the small wings of the sphenoid bone, which Geoffrey Saint-Hilaire