The Black Country NHS Foundation Trust, which treats people with mental health issues in Dudley, Sandwell, Walsall and Wolverhampton, used 270 qualified agency nurses between January 2012 and December 2012.
The trust spent £529,541 on qualified agency nurses over the last calendar year, a Freedom of Information Act request has revealed. The trust, which has a 2,000-strong staff payroll, employed the agency workers from a total of 18 different agencies in the region.
These were then asked to work at a variety of locations across the borough.
The trust was most in need of agency staff during the autumn.
In September, 44 qualified agency nursing staff were taken on to help out, while in October 45 were needed. This compares to January when just two extra nurses were required. The majority of these agency nurses were employed on mental health wards at facilities in Sandwell and Wolverhampton that provide 24-hour care.
Chris Oakes, director of workforce and learning at the trust, said: "Whilst the amount spent on agency nurses seems a high number, it is a very small proportion of the total wage bill for all the nursing staff we employ."
It comes after Sandwell and West Birmingham Hospital Trust, which runs Sandwell, Rowley Regis and City Hospitals, spent more than £1 million on agency staff in one month alone. The amount spent in February in 2012 was almost double the amount it has spent in other months.