Following a request from the European Commission, the Panel on Dietetic Products, Nutrition and Allergies (NDA) derived Dietary Reference Values (DRVs) for niacin. Niacin is a generic term for nicotinic acid and nicotinamide. Niacin can be synthesised in the human body from the indispensable amino acid tryptophan. Approximately 60 mg of tryptophan yields 1 mg of niacin defined as 1 mg niacin equivalent (NE). Long-term inadequate intake of tryptophan and niacin can lead to the development of pellagra. In the absence of new scientific data, the Panel endorses the Average Requirement (AR) for adults of 1.3 mg NE/MJ (5.5 mg NE/1 000 kcal) adopted by the Scientific Committee for Food (1993), based on data on urinary excretion of niacin metabolites as an endpoint. The Population Reference Intake (PRI) of 1.6 mg NE/MJ (6.6 mg NE/1 000 kcal) is derived from the AR assuming a coefficient of variation of 10 %. For infants aged 7-11 months, children and adolescents, as well as for pregnant and lactating women, the Panel considers that there is no evidence that the relationship between niacin requirement and energy requirement differs from that of adults; therefore, the AR and PRI for adults are also applied to these age and life stage groups.