The Scottish Stroke Care Audit found only five of the country’s 14 healthboards had succeeded in admitting at least 90 per cent of patients to a specialist stroke unit within a day of admission to hospital.
This has now been dropped from official targets, but the Scottish Government said it would continue to monitor hospital performance on the issue.
The report also revealed hospitals failing to hit other key standards, such as carrying out brain scans quickly and checking if a patient can swallow properly.
A so-called Heat target, set by the Scottish Government in 2011, said health boards should admit 90 per cent of stroke patients to a specialiststroke unit on the day of admission or the following day by March 2013.
But yesterday’s report revealed only five boards – Shetland, Ayrshire and Arran, Lanarkshire, Borders and Tayside – had achieved this standard by the end of March.
Following the introduction of the Heat target, the percentage of patients across Scotland admitted to a stroke unit within a day improved from 71 per cent in 2010-11 to 80 per cent in 2012-13.
But performance varied widely, from 100 per cent in Shetland to 67 per cent in Lothian and 63 per cent in Orkney.
In other areas, the report revealed improvements had been made.
Standards set by Healthcare Improvement Scotland say patients should be checked to see if they can swallow safely after a stroke on the day they are admitted to hospital.
In Scotland as a whole, performance in this standard increased from 47 per cent in 2005 to 68 per cent in 2012.
But the most recent figures showed this ranged from 96 per cent at the Gilbert Bain Hospital in Shetland to just 33 per cent at the Royal Alexandra Hospital in Paisley.
Elspeth Molony, interim director of the Stroke Association in Scotland, said: “We are disappointed to see that many hospitals are still falling short of the quality standards for stroke care and that there is a postcode lottery for stroke care across Scotland.
“We are particularly disappointed to see that only five of the 14 healthboards in Scotland have met the stroke Heat target.
“Despite the fact that almost two-thirds of health boards in Scotland failed to meet the target, it was allowed to lapse at the end of March meaning that there is currently no Heat target for stroke care.
“We are now working to ensure that a target is reinstated for April 2014 onwards.”
A Scottish Government spokeswoman said: “Ensuring people get access to a stroke unit as quickly as possible continues to be a priority for the Scottish Government.
“We are disappointed that this target has not been met but we still expect health boards to deliver this work, and will continue to be monitor this closely.
“Boards will be given enhanced support through an improvement team to help them deliver this as soon as possible.”