Liz Wray said she was shocked to see half a dozen pink mice emerge from multipacks of chips at a new Tesco store in Aston, Birmingham.
The mother of one said she was also horrified the store was not shut down straight away.
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Ms Wray told the Birmingham Mail she was with a work colleague when they made the discovery.
"Suddenly these tiny pink things appeared from the multipacks and were lying in front of us," she told the paper.
"They were repulsive and made me feel revolting. There were half a dozen of them crawling out of different holes in the crisps and we couldn't believe our eyes."
Tesco has apologised for the "upsetting" discovery and said it was confident the incident was isolated.
