Nicotinic acid blood level determinations were carried out in 30 male test subjects following application of xantinol-nicotinate in a new galenic retard preparation. The investigations showed that there is a continuous absorption of the agent--lasting for a longer period--with a maximum of blood level values between the 5th and 7th hour. In comparative studies with non-retarded xantinol-nicotinate the peak of concentration is already reached 1 h after application. The use of pharmacokinetic methods showed that by the retardation of xantinol-nicotinate there are no losses of absorption of nicotinic acid--as compared with the non-retarded forms. By the special galenic properties of the new retard form therapeutically effective nicotinic acid blood levels lasting for more than 8 h with an ascertained biological availability are attained.