Healthcare workers will watch the transition closely
Wales' healthcare system is beginning the first day of a new era after a major structural re-shuffle.
The country's five regional health authorities have been abolished in favour of 22 new local health boards matching local council boundaries.
The Welsh Assembly Government's aim is to benefit patients by ensuring decisions are made closer to their communities.
But the NHS Wales shake-up has proved controversial, with unexpectedly high transition costs having been revealed. Fears have also been expressed of a growth in bureaucracy.
Health Minister Jane Hutt decided the previous system - under which the authorities bought services from healthcare workers - was out of touch with patients.
AT A GLANCE: WALES' NEW NHS
Five health authorities replaced by 22 local boards (LHBs)
LHBs to get 75% of NHS Wales budget from assembly
They will pay hospital trusts, dentists etc. for services
Authorities' work taken on by National Public Health Service body
Health Commission Wales to control cardiac surgery, ambulances, some children's services etc.
She instead opted to pitch services at a more local level. Each new board will have 26 members comprising healthcare and community representatives plus one patients' representative.
The boards will have a wide brief, deciding how to spend their own budgets, which come directly from the Welsh Assembly Government, via three regional directorates. They also have executive teams.
Health trusts, which run most hospital services, will remain intact and are expected to provide services for the new boards.
Authorities' public health work transfers to the new, Wales-wide National Public Health Service organisation.
'Cost-neutral'
Some areas like cardiac surgery, emergency ambulance services and some children's services will remain controlled nationally and will come under the auspices of Health Commission Wales.
When Ms Hutt announced the plans in November 2001, she told the assembly her plan would be "cost-neutral".
But an independent audit has put the handover bill at �8.5m and a memo showed project leaders feared it escalating to �15.5m.
The assembly government has stood by its pledge, which it said on Monday was "challenging".
UK Chancellor Gordon Brown gave the plan an extra �49m at his 2001 pre-budget report.
AMs voted for the proposal by 31 to 24 despite fierce opposition criticism and fears the re-organisation could lead to more bureaucracy - precisely what Ms Hutt has said she wants to banish.
Dyfed Powys Health Authority, for example, has been split into boards for Carmarthenshire, Ceredigion, Pembrokeshire and Powys, raising fears about multiplication.
But the minister is confident a form of devolution for healthcare can turn around one of Europe's poorest health records.