The fall in real income between 2007 and 2012 ranged from 3.1 percent for accountants to 45.1 percent for notaries, Il Sole 24 Ore reported.
Despite the drop, notaries still have the highest income, earning an average of €107,400 in 2012, compared to an accountant's salary of €52,358.
The new figures, published by Adepp, the association for professionals, showed architects were worse off than most groups. They saw their income drop by almost a third to €20,535 last year, while those under 40 earned just €15,136 in 2012.
In the same five-year period the average engineer saw their income fall by 25.8 percent to €33,299, while the under-40-year-olds took home €23,954.
Lawyers remain among the highest earners, with an average salary of €47,402 in 2012 - a 17 percent cut since 2007.
While the professionals have been hit by the economic crisis, they have fared relatively well compared to other Italians.
The country’s national statistics agency, Istat, said on Monday that 29.9 percent of residents in Italy were at risk of poverty or social exclusion in 2012.
Half the families living in Italy survived on €24,634 a less in 2011, while those in southern Italy and the country’s islands lived on €20,129, Istat said.