Giving prepared remarks today are, in order of speaking, Senior Vice President and CFO, Rob McNutt; and President and CEO, David Fischer. Executive Chairman, Mike Gasser, will be available to answer questions during the Q&A session as well. I'll now turn the call over to Mr. McNutt.
Robert M. McNutt
Thank you, Deb. Please turn to Slide 4. While we fell short of our own end market expectations for the year, driven largely by weakness in Europe in the back half of the year, I don't want to lose sight of the fact that 2011 was a good year in several dimensions.
First, net sales were a record $4.2 billion, with solid contributions from all business segments. Second, operating profit before special items and asset gains was a record $382 million. Third, EBITDA before special items was $527 million, the highest in our history. And finally, earnings per Class A share before special items of $3.73 and the third highest in Greif's 134-year history.
Financial summary on Slide 5 includes key performance items for the fourth quarter on a year-over-year basis. 14% increase in net sales to $1.1 billion is primarily due to increased sales volumes of 7%, including 11% from acquisitions completed during the past 12 months, partially offset a 4% decline in same structure volumes. Higher selling prices that represented 4% and positive impact from foreign currency translation of 3%.
We experienced weaker market conditions and increased market pressures in the Industrial Packaging segment, especially in European markets in the second half of the year. Gross profit was $206 million for the fourth quarters of 2011 and 2010. Gross profit margin declined 2.6 percentage points at 18.2% of net sales in the fourth quarter. This was attributable to lower market demand in Rigid Industrial Packaging, increased manufacturing cost, overall product mix and higher OCC costs for Paper Packaging compared to the same quarter last year.