Bradford Teaching Hospitals NHS Foundation Trust was the worst-performing trust in Yorkshire during October, with just 73.3 per cent of patients seen within the target four-hour window.
Data for Mid Yorkshire Hospitals NHS Trust and The Rotherham NHS Foundation Trust was not available.
Second-worst on waiting times was York Teaching Hospital NHS Foundation Trust, where just 80.7 per cent of patients were attended to within four hours.
Sheffield Teaching Hospitals NHS Foundation Trust also fell below the operational NHS standard, with 82.9 per cent of patients seen within the expected four-hour window.
16.7 per cent of A and E patients were left waiting for longer than four hours in Hull And East Yorkshire Hospitals NHS Trust hospitals in October.
In the same period, Leeds Teaching Hospitals NHS Trust saw a rate of just 85.2 per cent of patients seen within the target four hour window in A and E.
Not far ahead is Airedale NHS Foundation Trust, where just 85.4 per cent of A and E patients are likely to be seen to within four hours.
Also behind the national NHS waiting time target is Calderdale And Huddersfield NHS Foundation Trust. 87.8 per cent of A and E patients were seen at this trusts hospitals within four hours.
Doncaster And Bassetlaw Teaching Hospitals NHS Foundation Trust saw a rate of 90.3 per cent of patients seen to within four hours, lagging behind the target of 95 per cent.
With similar stats, Harrogate And District NHS Foundation Trust hospitals tended to just 90.4 per cent of A and E patients within four hours.
Barnsley Hospital NHS Foundation Trust was one of just two Yorkshire NHS trusts to surpass the national target of 95 per cent. It just managed this, with 95.2 per cent of patients seen in the four hour window.
Sheffield Children's NHS Foundation Trust performed the best in October, with 97.8 per cent of patients in A and E seen to within four hours.