We have analysed the haematological parameters in 21 patients with Shwachman‐Diamond syndrome (SDS) seen over a 25‐year period at our institution. Neutropenia, although present in all patients, was intermittent in two‐thirds, constant in the rest and was associated with impaired chemotaxis in all of those patients tested. Fetal haemoglobin (HbF) was elevated in 80% of the patients at some stage, and anaemia and thrombocytopenia was documented in 66% and 24% respectively. Bone marrow samples were taken in over half of the patients. Myelodysplastic syndrome (MDS) developed in seven (33%) patients, five of whom had acquired clonal structural chromosome abnormalities in their bone marrows. In five of the patients with MDS (24%) transformation to acute myeloid leukaemia occurred. Like other constitutional bone marrow failure syndromes, SDS has a predilection to leukaemic transformation hitherto assumed to be in the region of 5–10%. The data presented here suggest that this figure probably represents an underestimate. Shwachman‐Diamond syndrome is an interesting model of leukaemia development and greater understanding of the clinical spectrum of this rare disorder should produce further insights into its pathobiology.