The clusters from size-fractions of hydrolysed amylopectin from amylose-free potato starch (APP) were isolated by controlled α-amylolysis. The external chains were removed by further phosphorolysis and β-amylolysis, thereby transforming the APP and the clusters into Φ,β-limit dextrins. The DP of the Φ,β-LD of the clusters was rather uniform around 40-50. The unit chain composition was analysed by HPAEC-PAD and it was shown that the long internal B-chains, that interconnected the clusters in the amylopectin, had preferentially been cut into B-chains with DP 8-23. Smaller clusters possessed also increased amounts of the shortest B-chain with DP 3. The A:B-chain ratio decreased after α-amylolysis, showing that A-chains were not formed. The clusters were built up of only 4-6 chains and the density of branches was 11-13%. Very small, branched building blocks were also isolated from the APP and the clusters by an extensive α-amylolysis and analysed by GPC and HPAEC. The building blocks ranged between DP 5-30 and contained 2-5 very short chains (approx. CL 2-7). The predominating branched building blocks had DP 7-8 and were singly branched. The density of branches within building blocks was high (25%) and the clusters were at average composed of 2 or 3 building blocks.