They show that while the number of people working at large agencies has gone down by 4 per cent, medium-sized and smaller shops have increased their workforces by the same amount.
Overall staff levels dropped by an average of 2.5 per cent last year.
This bears out the theory that big shops are suffering disproportionately because of the need to satisfy US parent companies' demands and the huge impact on jobs when a major account leaves.
The statistics also reveal agencies remain staffed overwhelmingly by people from white British backgrounds; only 4 per cent of employees come from ethnic minorities.
The census also found that women are still finding the career ladder difficult to climb. Despite comprising almost half of the industry's total staff, only 10 per cent of agencies' chairmen, chief executives and managing directors are female.
And as the IPA kicks off a major initiative to increase numbers of female creatives, figures show that 87 per cent of art directors and 80 per cent of copywriters are men.
Meanwhile, despite the UK population ageing, the majority of staff are between 25 and 34 years old, with only 12 per cent aged 45 and over.
Hamish Pringle, the IPA's director-general, said the figures reflected the diversity of IPA member agencies and the fact that there were areas of growth as well as decline.
An estimated total of 14,200 people were working in IPA agencies last year. The figure was 200 more than during the corresponding period in 2001, but is accounted for by the fact that seven more agencies took part in the 2002 census.
- Perspective, p4.