New figures collated by the Royal College of Physicians show eight per cent of stroke patients now receive the treatment, called thrombolysis. Experts say some 20 per cent of patients are clinically suitable for the drugs, which have to be administered within about four-and-a-half hours of a stroke to be effective.
The rise follows a push, as a result of the 2007 National Stroke Strategy, to increase use of clot-busting drugs.
Studies show thrombolysis can reduce the chance of death and serious disablity in stroke. An estimated 150,000 people have a stroke in Britain every year, while they account for about 53,000 deaths.
The audit suggests that most stroke patients who do not receive thrombolysis are failing to do so because they do not get to a hospital's stroke unit in time.
Just over half (53 per cent) are admitted to a stroke unit with four hours. A third are first admitted to other parts of a hospital before being referred to the stroke unit, which often means they get there too late for clot-busting drugs treatment.
The RCP also expressed concerns that poorer performing hospitals may be refusing to submit information - leading to an overly-rosy picture.
Professor Tony Rudd, chair of the Intercollegiate Stroke Working Party and director of the RCP stroke programme, said: "Acute stroke services are improving in England albeit from a low base. "Not all hospitals contributed to this national audit and one has to be concerned that the quality of care in the non participating hospitals may be lagging behind those who have been willing to share their data."
Joe Korner, of The Stroke Association, said that although there were "excellent results" from some parts of the country "unfortunately some hospitals are falling short".
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More stroke patients getting clot-busting drugs