It was an 80 million euro, or 23 per cent, increase on the previous season's loss.
Only 19 of the 107 clubs across the top four divisions surveyed made a profit.
Football as a whole was in decline as it generated 2.5 billion euros, a 1.2 per cent decrease on the previous campaign.
Serie A, unsurprisingly, accounted for the majority of that (82 per cent) although that was 2 per cent less than its share in 2009/2010.
Production costs increased by 1.5 per cent to 2.9 million, which created the 428 million euro loss.
However, it was noted that the rate of increase in production costs reduced significantly from 6.8 per cent in 2009/10 and 6.4 percent in 2008/09 to just 1.5 per cent this time around.
Part of the increased loss can be explained by a drop in attendances of 4 per cent across the four divisions.
There were 13.3 million people passing through the turnstiles in 2010/11.
The drops increase the lower the division with Serie A seeing only a 2.4 per cent reduction while the fourth division saw an almost 20 per cent drop.
That resulted in a 22.4 million euro fall in gate receipts in professional football from 275.4 million euros to 253 million euros.
Gate receipts amount to only 10 per cent of Italian clubs' revenue.
Stadiums were on average 56 per cent full with the Champions League matches performing best at 67 per cent of capacity, followed by Serie A with 59 per cent.
Fourth division games record only 20 per cent turnouts.
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