This randomized, double-blind, placebo-controlled, counterbalanced, repeated measures . -1experiment examined the effects of a 5 mg kg body weight dose of caffeine on delayed onset muscle pain intensity and force loss in response to 64 eccentric actions of the dominant quadriceps induced by electrical stimulation. Low caffeine consuming college-aged females (N = 9) ingested caffeine or placebo 24 and 48 hours following electrically stimulated eccentric exercise of the quadriceps. One hour after ingestion, maximal voluntary isometric contractions (MVIC) and submaximal voluntary eccentric actions were used to determine whether caffeine attenuates muscle pain intensity or force loss during activation of damaged quadriceps. Pain intensity was measured using a 0 to 100 visual analog scale. Caffeine produced a large (12.7 raw VAS units; -58.4%; d = -0.88) statistically significant hypoalgesia during the MVIC (t = -2.52; df = 8; Pone-tailed = 0.018) and a smaller reduction in pain scores during submaximal voluntary eccentric movements (7.8 raw VAS units; -25%, d = -.34; Pone-tailed = 0.179). Caffeine produced a small increase in MVIC force (5.3%; d = 0.12; Pone-tailed = 0.095). The results suggest that adenosine contributes to delayed onset muscle pain and adenosine antagonists are useful in treating this type of muscle pain among low caffeine consumers. KEY WORDS: adenosine antagonist, DOMS, force, electrical stimulation, isometric, soreness