MMAFighting.com has the word from Nevada State Athletic Commission executive director Keith Kizer:
(Brock) Lesnar and (Shane) Carwin were among those tested and the results came back clean. The NSAC has traditionally tested both main event fighters, though all fighters are subject to random testing.
Also tested and cleared were co-main event participants Chris Leben and Yoshihiro Akiyama along with Chris Lytle, Matt Brown, Krzyzstof Soszynski, Stephan Bonnar, Brendan Schaub, George Sotiropoulos, Kendall Grove, Ricardo Romero, Jon Madsen, Gerald Harris and Daniel Roberts.
Not tested were Kurt Pellegrino, Chris Tuchscherer, Seth Petruzelli, Goran Reljic, Dave Branch, Forrest Petz and Karlos Vemola. In all, 15 fighters were tested while seven were not.
It's good to see the fighters continuing to not test positive. The report notes that no UFC fighter has tested positive since Karo Parisyan at UFC 94 in January 2009.