All UFC on Fox 1 drug screens came back clean, Sherdog.com confirmed with the California State Athletic Commission on Thursday.
Ten fighters were tested for steroids following the event, including dos Santos, Velasquez, Ben Henderson, Clay Guida, Ricardo Lamas, Clay Harvison, Mackens Semerzier, Cub Swanson, DaMarques Johnson and Robert Peralta.
Meanwhile, dos Santos, Velasquez, Henderson, Guida, Lamas, Harvison, Semerzier, Swanson, Johnson, Peralta, Aaron Rosa, Matt Lucas, Pablo Garza and Dustin Poirier were all tested for drugs of abuse, such as cocaine.
UFC on Fox 1 marked the promotion's first appearance on network television. The show served as a prologue for the UFC's seven-year broadcast deal with Fox Networks, which begins in January 2012.