MSN's free unmoderated chatrooms are shutting down in the UK, Europe, Middle East, Latin America and most of Asia.
There have been a spate of cases of paedophiles using chatrooms
The decision was announced by Microsoft at the end of September and was welcomed by children's charities as a positive step to ensuring safety online.
The move followed a spate of cases that provoked concern about unmoderated chatrooms being used by paedophiles to groom children for abuse.
But at the time of the decision major net service providers criticised the action as "irresponsible" and insisted it was driven by business motives rather than keeping children safe.
Net experts also warned it could drive vulnerable young people to other unmoderated chatrooms on the net.
Chatrooms on MSN's other global sites will either be supervised - or moderated - by an adult 24 hours a day, or will be on a credit card subscription-basis only.
Douglas Lindsell, thought to be one of the most persistent and prolific groomers of children over the internet, was
last week jailed for five years.
The 64-year-old, from south-west London, had made up detailed profiles of 54 youngsters from the UK and 19 from abroad.
The paedophile was known to use MSN chatrooms to search for potential victims.