The man's intestines had been wrapped carefully in two containers, Austrian media reported.
The woman, who has not been named, explained that she suspected her deceased husband had been poisoned, according to Kleine Zeitung.
She wanted a toxicology test carried out on her husband's tissue.
He died during an operation in Morocco, the newspaper reported.
When the woman arrived in Graz, a doctor was called to examine the intestines but said a proper investigation could not be carried out without the whole body.
Police said the woman had not broken any laws. The entrails have been stored temporarily ahead of further forensic investigation.
Bemused customs officials in Austria have stopped a Moroccan woman, who travelled to Graz airport with a bag containing her husband's entrails.