The youngsters at Tweedbank Primary in the Borders have been told to leave behind their broomsticks and teachers have ditched their dooking apples and neep lanterns after a parent is believed to have objected.
One parent said: "The children were looking forward to Hallowe'en but then we were told they weren't allowed to dress up or do any of the games you would associate with it.
"All we have been told is that one parent objected to their child taking part.
"The whole thing is ridiculous. They'll be cancelling Christmas next."
Hallowe'en derives from the old Celtic festival of "Samhain", the Old Irish for "summer's end".
Tweedbank headteacher Alyson Weir said an optional Hallowe'en event will now take place for pupils, adding: "In order to respect all family beliefs and values, we have decided to run the advertised session as a normal nursery session."