In the photo Tamra, 51, laid on a hotel bed while dressed in her wedding dress.
This appears to be the gown she wore when she wed her first husband Darrien Vieth in 1985. They share controversial son Ryan Vieth.
"Do you know someone that is in need of a size 2 WHITE wedding dress" she asked her followers. "I’m giving my wedding dress away to someone in need."
"It’s in perfect condition (only worn once)," she continued. Tamra said she would announce the winner of her contest this weekend.
Fans repeatedly asked Tamra if the dress was blue as it appeared that way in the photo she posted. The Cut Fitness owner said it was white and blamed how it looked on the age of the snap.
Tamra revealed that her daughters, Sidney and Sophie, don't want the dress after a fan asked if either would keep it for one of their future nuptials.
The mother-of-four has walked down the aisle three times. She married her second husband Simon Barney in 1998. They split for good in 2011.
She married her third husband Eddie Judge in 2013. Their nuptials were aired on the RHOC spinoff Tamra's OC Wedding.