Two hospital NHS trusts have finally merged after nine years of planning, legal challenges and delays.
The combined trusts of Poole Hospital and Royal Bournemouth and Christchurch Hospitals are now called University Hospitals Dorset NHS Foundation Trust.
The £147m reorganisation had been due to happen by 1 July but was further delayed by the Covid-19 pandemic.
Chief executive Debbie Fleming said the new organisation would be "much stronger and more resilient".
"We will be attracting the very best people from all over the country to come and work in this part of the world," she said.
Substantial work is still required at the two main sites, including a six-storey extension at Bournemouth, before the main changes can take effect.
Under the plans, Poole's emergency department will be downgraded and its maternity and paediatric services will move to Bournemouth, which will also become the area's main emergency hospital.
Poole will become a centre for planned treatment and operations.
The merger is the fruition of almost a decade of planning. Initial proposals were rejected by the Competition and Markets Authority.
Campaigners opposed to the plans took their case to the High Court in 2017 and 2018, but judges ultimately ruled in favour of Dorset Clinical Commissioning Group (CCG) which planned and continues to oversee the reorganisation.
The new trust employs more than 9,000 staff and has an annual turnover of more than £630m.