Soaring obesity and alcohol consumption blighted the NHS's "considerable progress" under the Labour Government, a study has concluded.
Hospital waiting times were slashed and access to primary care improved since 1997, a report by thinktank the King's Fund said.
But while there was progress in making the NHS more accountable and transparent to government and taxpayers, the service is still failing to tackle obesity and alcohol effectively, the study indicated.
The report concluded: "This review has found that progress has been more elusive in reducing harm from alcohol and rates of obesity.
"Consumption of alcohol has increased since 1998, accompanied by a rise in alcohol-related hospital admissions and rates of liver disease, suggesting more aggressive, cross-departmental action will be needed in the future.
"The prevalence of obesity is rising in adults and children, despite government targets to halt the increase. There has been improvement in rates of exercise and aspects of healthy eating, but it is too soon to evaluate some of the more recent government initiatives to reduce obesity.
"However, the predictions of significant increases in obesity-related ill health in the future mean that the next government will need to sustain investment in initiatives delivered by the NHS and all other relevant agencies."
The 108 page report - entitled A High Performing NHS? - said the health service became a priority for voters in the build up to the General Election.
Concluding its progress report since 1997, it added: "In summary, there is no doubt that the NHS is closer to being a high-performing health system now than it was in 1997.
"It is capable of delivering high-quality care to some patients, in some areas, some of the time. Even though there are considerable financial challenges ahead, the next government must aspire to create an NHS that can deliver quality to all patients, in all areas, all of the time - in a way that is demonstrably fair, efficient and accountable to the society that pays for it."