YouGov's pre-tax profits totalled £2.97m in the six months to January, compared with £2.31m in the same period the year before. Group turnover soared 208% to £18.8m.
However, the impact of the acquisitions of Polimetrix in the US, Psychonomics in the Germany and Zapera in Denmark, meant that overall pre-tax margins fell from 38% to 15.7%.
Nadhim Zahawi, chief executive of YouGov, said that the company's challenges include "growth and integration while maintaining profitability".
The company said that current trading was in line with expectations, and that the three acquired businesses are "delivering the expected benefits and synergies".
Zahawi added: "We are benefiting from the considerable investment we are making across the group which, combined with the international opportunities we have identified, make us confident that 2008 will be another successful year.
"The second half has started well with the momentum seen in the first half continuing and trading in line with the board's expectations."