To determine the analgesic effect of ethanolic extract of Nigella sativa seeds on experimentally-induced pain in albino mice. Randomized controlled trial (RCT). Physiology Department, Services Institute of Medical Sciences (SIMS), Lahore, from May to September, 2009. The study was carried out in 90 male albino mice using acetic acid induced writhing test as a chemical model of nociception. The mice were divided in three groups of 30 each. Group A was given normal saline (control); group B was given Nigella sativa seed extract in a dose of 50 mg/kg; and group C received diclofenac sodium, as a reference drug. Number of writhings in treated and control groups were compared. The ethanolic extract of Nigella sativa seeds given intraperitoneally caused significant (p < 0.05) analgesic effect on nociceptive response initiated by 0.6% acetic acid; although this analgesic effect was less than that produced by diclofenac sodium. Ethanolic extract of Nigella sativa possessed significant analgesic effect in mice.