A Perth woman says she is “angry and sickened” after her two-year-old daughter allegedly found a used condom at a McDonald’s in Warnbro - and put it in her mouth.

The mother, known only as Wendy, said she visited the fast food chain with her husband and child about 6pm on Friday night.

She said she was at the counter placing an order, having left the little girl with her dad, when the discovery was made.

“I don't know how it happened but when my husband next looks at her, she's sucking on a black condom," Wendy told 10daily.com.au.

Camera Icon The used condom allegedly found at a McDonald’s store in Warnbro. Credit: Supplied

The girl’s horrified father grabbed it off her and quickly showed it to staff before Wendy ran into the bathroom to wash her daughter’s mouth and hands.

Wendy believes her daughter found the used condom on a chair.

"I am really angry and sickened ... I haven’t slept. I have been feeling overwhelmingly guilty for taking her there in the first place," she said.

The family will “have to wait two months” before doctors carry out blood tests to determine if the girl has contracted anything.

A McDonald’s spokesperson said the company was “very sorry that the incident occurred, and take situations like this seriously”.

“We are conducting an investigation into how this happened,” they said.

"Cleanliness and safety are our top priorities and we ensure the shift manager on duty conducts what we refer to as a travel path every 30 minutes."