A 64-year-old man had a several year history of B prolymphocytic leukaemia (PLL) which behaved indolently and had not required any treatment. Five years after diagnosis, he developed hypoalbuminaemia associated with severe lower-limb oedema, consistent with systemic capillary leak syndrome (SCLS). He recovered spontaneously but went on to have three further increasingly severe and protracted episodes over the subsequent 18 months. There was no identifiable precipitating factor for these episodes, but his peripheral lymphocyte count continued to increase slowly. The start of treatment for his PLL with chemoimmunotherapy was followed by a rapid resolution of residual oedema and normalisation of serum albumin. He has had no further attacks of SCLS in the 14 months since he started therapy for PLL. SCLS is a rare consequence of haematological malignancy which may show an excellent response to treatment of the haematological disease.