Health revenues were up from £20.1m to £24.2m, but consumer division income dipped from £41.5m to £39.1m.
In the six months to the end of June, Cello reported pre-tax profits on continuing operations declining from £1.4m to £917,000.
Mark Scott, chief executive, said: "Cello continues to make strong headway implementing its stated strategy.
"Cello Health is becoming established as a leading business in the global pharmaceutical market.
"The group's international revenues are growing, the group's value added advisory revenues are growing, and our web capabilities are cutting edge."
The health arm – incorporating market research business Insight, medical communications firm MedErgy and consulting company MSI – was boosted by international work, particularly in the United States.
The consumer business – which includes Edinburgh-based online marketing company Blonde Digital and public relations firm Stripe Com- munications as well as Leith – saw a slowdown in research activity for clients during the period although there has been an improvement in recent trading.
Leith, best known for its work with Irn-Bru and Tennent's, was highlighted as performing ahead of expectations.
Recent high-profile campaigns include breast cancer awareness adverts featuring actress Elaine C Smith.
Cello chairman Allan Rich said: "The group has made material investments behind developing a suite of web-based analytical tools to reinforce its social media research and advisory capabilities, hosting communities and allowing analysis of social media activity for clients, particularly through mobile devices.
"Cello Consumer has also worked hard to introduce new international revenue streams. It now has offices in San Francisco, New York, Singapore, and will shortly open in Hong Kong.
"This will progressively increase Cello Consumer's dependence on non-UK client activity.
"The board is confident that Cello Health will continue with its strong performance over the full year and that the growth investments made will promote longer term expansion."
Cello booked a charge of around £700,000 for restructuring and provisions for empty properties in the first half.
It also spent around £300,000 on new premises and start-up costs with the New York health office doubling in size in September.
The Philadelphia office is pencilled in to grow, with a further North America base planned over the next 12 months. A Hong Kong office is also on the drawing board.
Clients include Bayer, Pfizer, Boots Opticians, the NHS, Shire Pharmaceuticals, Diageo, the Scottish Government, General Motors, Unilever and adidas.
Shares in Cello ended the day unchanged at 39p.
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