Revenue was £815.7m for the six months ended 30 September 2012, which is down 3.2% compared with the same period last year. However, last year's figures included the UK asset management business that was disposed of in November 2011 and contributed revenue of £20.2m.
Underlying operating profit was down 11% to £45.9m.
Globally, staff numbers were 17,756 at the end of September, a 2% increase on the position at 31 March 2012. Average staff numbers, excluding the effect of the asset management disposal, were up 3% year on year.
Excluding the divested business, UK staff numbers were up 3.5% to 9,169 by 30 September. Further growth is expected and 500 graduates are being taken on this autumn
UK revenue and operating profit were both virtually unchanged from H1 2011 at £420.5m and £24.8m respectively.
US operations suffered from a hiatus in work in the run-up to the presidential election.
Chief executive officer Uwe Krueger said: "The group has delivered encouraging results in line with our expectations, with the sector and geographic spread of our business continuing to provide resilience in challenging markets. Implementation of our strategy continues and the outlook for the full year remains unchanged.
“We are pleased to be recruiting again and, in particular, are delighted to welcome over 500 graduates to the group this autumn.”
Atkins is one of the world's largest engineering design firms and was the official engineering design services provider for the London 2012 Olympic and Paralympic Games.