We examined cytokine production and allergic reactions in mice fed ad libitum (AL) and subjected to dietary restriction (DR). DR retarded the increase in body weight, and peripheral blood T cells in the DR mice produced less IFN-gamma and more IL-4 in response to immobilized anti-CD3 mAb. Systemic immunization and intranasal challenge with ovalbumin (OVA) induced accumulation of leukocytes into the lung, increase in IL-4 level in bronchoalveolar lavage fluid (BALF), and rise in serum IgE in the AL mice. In contrast, these allergic symptoms were alleviated in the DR mice. Furthermore, the relative proportion of IL-4-producing T cells responsive to OVA was less in the DR mice than the AL mice. DR tended to decrease the proportion and cytolytic activity of NK cells in the spleen, especially in younger mice. These results indicate that DR can prevent the expansion of allergen-specific IL-4-producing T cells followed by suppression of the allergic reaction, but might dampen NK cell activity.