On today's conference call, non-GAAP financial measures will be used to help investors understand Hospira's base business performance. These non-GAAP financial measures are reconciled to the comparable GAAP financial measures in the press release and Form 8-K issue this morning, and are also available on the Presentation page on the Investor Relations section of our website.
Also posted on our website is a presentation of complementary materials that summarize the points of today's call. While we will not be speaking directly to the materials, it is posted on the Presentation page at www.hospira.investor.com. The material is for your reference to use as an enhanced communication tool.
Finally, we will be ending the call at the top of the hour this morning. In order to allow as many of you as possible to ask a question, we're limiting each person to 1 question. We ask for your cooperation in this respect.
And with that, I'll now turn the call over to Mike.Thomas E. Werner Thanks, Mike. Good morning, everyone. First, I'd take you to a brief review of the income statement for the fourth quarter and 2011. Adjusted gross margin as a percentage of sales in the quarter was 34.0%, down from 39.1% in the fourth quarter of 2010. This was due primarily to inventory losses in certain quality actions. For the full year, adjusted gross margin finished at 38.5% which was in line with our revised guidance for the year. Research and development expense in the fourth quarter was $67 million or 6.6% of revenue. For the full year, R&D expense was 6.4% of revenue. SG&A expense in the fourth quarter was $167 million or 16.5% of revenue. And for the full year, SG&A as a percentage of revenue was 15.7%. Adjusted operating income was $111 million compared to $142 million in the fourth quarter of last year. For the full year, adjusted operating margin was within our revised guidance range at 16.5%.