A series of experiments were conducted to examine the effect of single oral doses of ascorbic acid on body temperature in healthy guinea pigs. Fifteen male guinea pigs (approximately 200 g) were fed a nonpurified diet designed for rabbits (a scorbutogenic diet) ad libitum and received orally 2 mg L-ascorbic acid/100 g body wt daily. After acclimation, rectal temperatures were recorded hourly following five separate ascorbate dosage treatments: 0 (control dosage), 2, 10 or 50 mg ascorbic acid/100 g body wt, or 50 mg ascorbic acid and 0.07 mg indomethacin/100 g body wt. Mean body temperature was significantly elevated (P less than 0.05) after 1 h in animals receiving either the 10 or 50 mg dosage (+ 0.27 +/- 0.05 and + 0.41 +/- 0.07 degree C, respectively) compared to that in animals receiving the 2 mg dosage (-0.07 +/- 0.05 degree C), the recommended daily intake for guinea pigs. Changes in body temperature of animals receiving the 50 mg dosage plus indomethacin did not differ significantly from those reported with the 2 mg dosage. Thus, a single oral dose of ascorbic acid at levels 5-25 times the recommended intake, can elevate body temperature significantly in healthy guinea pigs, a phenomenon which is inhibited by indomethacin administration.