Differences in the allocation of funds by NHS trusts to tackle serious ailments such as heart disease and cancer have remained practically unchanged for three years, according to a report.
Even when the specific health requirements of local people are taken into account, huge differences remain in how much primary care trusts (PCTs) spend on certain illnesses.
Some of this could be down to decisions by individual doctors about who to treat while some hospitals may not operate as efficiently as others.
Professor John Appleby, chief economist at the King's Fund, who compiled the report, said more research was needed but the study did raise questions about the "consistency of the decisions PCTs make about how much they spend on different diseases."
He added: "This latest analysis reveals that the widespread variations in PCT spending on different diseases have remained relatively unchanged over the past three years.
"Even when local need and other legitimate reasons for variations in spending are taken into account, PCTs continue to spend varying amounts on cancer, coronary heart disease, mental health and a range of other diseases.
"Some of the variations we have highlighted will not solely be as a result of deliberate choices by PCTs.
"Other factors, such as variations in decisions by clinicians about who and when to treat, and what treatment to provide, and differences in the efficiency of hospitals, will also contribute to these variations."