If used appropriately, peppermint oil can be effective in repelling mice. Be sure to use 100% pure peppermint oil, designed for repelling mice and pests.
To use peppermint oil as a mouse repellent, you'll need peppermint oil and cotton balls. Put at least five drops of oil on each cotton ball. The scent of the peppermint must be strong enough to act as a deterrent to the mice. Once the cotton balls have been treated with the oil, they can be placed strategically to repel mice. For example, cotton balls along the perimeter of a house will keep mice from entering the home. However, this strategy will not work to rid a home of mice if they're already living within the house.