After the repeated dosing of linear or macrocyclic GBCAs in rats, the brain was fractionated 3 and 24d p.i. Cerebrum, cerebellum and pons were separated, homogenized and divided into an insoluble and soluble fraction, which was separated into low and high molecular weight molecules. The gadolinium concentration in the brain was very low. A large portion of the Gd in the linear GBCA groups was found in the insoluble fraction and a smaller portion in large macromolecules. The Gd in the macrocyclic GBCA groups was only found in the soluble fraction and in small molecules. Gd excretion was still ongoing.