We have addressed the question of whether dietary nucleotides contribute to the liver nucleic acid pool and whether this contribution is related to age. Two experiments were performed in rats of 1 months, 3 months and 17 months of age. In the first, rats were fed a nucleotide-free diet or the same diet, but supplemented with nucleotides for 3 and 10 days. In the second experiment, rats were starved for 3 days. Liver RNA decreased by 10-day deprivation of dietary nucleotides and starvation in young and adult rats but not in the old. Liver DNA decreased by starvation in adult and old rats but not in the young, whereas nucleotide deprivation had no effect. These results, demonstrating that dietary nucleotide deprivation causes an effect on liver RNA pool similar to the effect of starvation, indicate that dietary nucleotides contribute to the liver RNA pool, this influence being related to age.