Many of the children at St James' Primary in Renfrew take a council-run bus to school every day, but have to make their own way to the entrance once they are dropped off.
Three other primaries in the area - St John Bosco, Kirklandneuk and Rashielea - have staff who chaperone children from their buses, and parents want St James' to follow their lead.
Ninety-eight pupils from P1 to P7 take the council-organised transport and have to walk to the back of the school unsupervised after leaving the bus.
The area is not restricted and parents worry that, without an adult present, children could be at risk of wandering off on their own or being approached by strangers.
A former teacher, whose grandchildren attend the school on Albert Road, was so worried about childrens' safety that she asked for a risk assessment to be carried out.
She was also informed by the council that the current process was in line with their policies, and no changes would be made.
The 64-year-old woman, who did not want to be named, said: "Any wee one that an adult goes up to and says 'Come with me, your teacher says you have to come with me' would just go with them. There's no adults there, the kids have got their packed lunches, dinner money and things. I met a parent there the other day and she said that two days in a row she put a child into the school playground because she got off the bus and she was running around the street."
MSP Derek McKay contacted Renfrewshire Council in a bid to try to resolve the problem.
He said: "After my investigations I was informed that the response was in line with council policy and that this was appropriate and reasonable.
"I was also informed that some of the issues would be resolved when the school moves to the new St James building that is currently under construction. As this has now been delayed, I have contacted Renfrewshire Council again for an update on this situation and the implications of any delay."
A spokesman for Renfrewshire Council said classroom assistants wait at the back entrance of the school, but not at the drop-off point, and the area is covered by CCTV. He said: "We would stress that the current access arrangements are in no way unsafe.
"Children are supervised as they enter the building as in any other school. The school and parent council representatives have tried different approaches to reduce the number of people within the school grounds."