Dog faeces are causing a stink at St Gerard's School in Alexandra.
Deposits of dog poo, placed in small plastic bags, are being flung into the school's bushes - daily.
The problem is so bad school principal Trina Eastwood is considering installing surveillance cameras.
Mrs Eastwood said the issue had been raised within the school community and now she wanted to express those concerns more widely in the hope the culprit would be caught.
''We are just really disappointed that somebody in the community would choose school grounds to drop off their dog's poo.''
The bags are knotted, ensuring the contents did not spill out.
However, staff thought any consideration went down the toilet the minute the culprit decided to fling it over the fence, off Station St, into the school's grounds.
Mrs Eastwood said about half a dozen of the small bags were left on any given day, sometimes more.
Eleven of the bags were found by the school's caretaker Mark Eastwood on Friday morning, dumped among shrubs where children often play and take part in school activities.
Small black bags containing dog poo was something he had come across on a daily basis over the past year.
''It's just become ridiculous.''
He urged the culprit to show some respect, particularly as the children often played in the vicinity. They also used the area for a predator identification project, often crouching down to investigate predator footprints.
Mrs Eastwood said no area of school grounds was off-limits to the children who often made huts among the shrubs and climbed trees.
She urged anyone who saw people acting suspiciously in the area or throwing anything over the fence to report the matter to the school.
