Chocolate which contains flavonoids, a group of compounds which may exhibit biological activity, is made of Theobroma cacao beans. It is strongly suggested that certain dietary flavonoids may have the potential to reduce the risk of many diseases. Flavonoids have strong antioxidant potential, so they may help to maintain the cardiovascular health and can influence immune response. Polyphenols from cacao liquor can inhibit mitogen-induced proliferation of T cells and polyclonal Ig production by B cells in vitro. They also influence IL-2 secretion by T cells. Chocolate is used by people as a form of self-medication for dietary deficiencies (e.g. magnesium) or to balance low levels of neurotransmitters involved in the regulation of mood, food intake and compulsive behaviours. However, our previous research performed in mice showed that chocolate and substances contained in it have many unfavourable effects on organism during its development, e.g. they lower embryos mass and their tissues angiogenic activity. Moreover, such treatment was found to cause the shortening of the limbs in offspring of mice fed chocolate during pregnancy, and disturbed the process of bone mineralization. The aim of the present paper is to examine the possible influence of chocolate feeding of pregnant and lactating mice on the cellular and humoral immunological response of their six-week old progeny. We have found, that a daily dose of 400 mg of chocolate given to pregnant and lactating mice resulted in the enhancement of humoral immunity and suppression of cell-mediated immunity of their 6 week-old progeny.