New UKIE research shows that only two out of five parents buy games with a suitable age rating, while 43% said they checked ratings but didn't necessarily stick to them.
Of the parents who said they never check age ratings, 24% believe that video games are unlikely to contain unsuitable content.
The research also revealed that video games are the most sought after presents this year, with 33% of children requesting a new game or console, compared to 29% asking for books.
Some 53% of parents, meanwhile, will buy a video game as a present, with 59% of those parents likely to play the game with their child.
"At Christmas there is a fantastic variety of games for parents to choose from, for their families to enjoy," explained UKIE CEO Dr Jo Twist.
"PEGI ratings on all UK games give clear and simple guidance on the suitability of games for different age audiences and if parents need further guidance on what these ratings mean they can visit Ask About Games.
"We'd urge parents to use this really helpful tool to ensure that playing games has the biggest positive impact on their children and family as a whole this Christmas."
PEGI became the sole age rating system for video games in the UK in July, taking over from the BBFC.
The rating system is enforceable by law in the UK, where selling a game to someone underage can result in a possible £5,000 fine and a jail sentence of up to six months.
A Digital Spy poll carried out in the aftermath of the switch found that nearly three quarters of consumers ignore video game age ratings.