This study was performed to determine if experimental subjects given ascorbic acid (AA) in a 240-mg dose every 4 days maintain blood levels of AA similar to levels of control subjects given 20 mg three times per day. All subjects ingested foods providing 6 to 7 mg AA/day but adequate in other nutrients. Mean serum AA for all subjects was 1.26 mg/dl initially indicating a habitual AA intake of over 100 mg/day. After 32 days on 66 mg AA/day, mean serum AA of control subjects remained below 0.7 mg/dl. After the first depletion period experimental subjects had significantly lower (p less than 0.05) serum AA than control subjects (0.74 versus 1.02 mg/dl). By the third depletion period experimental subjects adjusted to the less frequent dosage such that serum levels of AA were not lower. They were sometimes significantly higher (p less than 0.05) 1 day after the 240-mg dose. Experimental subjects had similar or higher mean white blood cell AA throughout the experiment. White blood cell AA was significantly (p less than 0.05) and negatively correlated with white blood cell count (r = -0.65) Results suggest that subjects adjust to receiving supplements of AA on a periodic basis at least under the conditions imposed in this study.