Although the presence of anaemia after renal transplantation is well known, specific data on the prevalence and risk factors are scarce. Results from the recent TRansplant European Survey on Anemia Management (TRESAM) survey, conducted in 4263 recipients of a renal transplant from 72 centres in Europe, revealed that 38.6% of patients were anaemic [haemoglobin (Hb) concentrations < or =13 g/dl for male patients and < or =12 g/dl for female patients]. Of these patients, 11.6% had moderate anaemia (Hb concentrations >11 and < or =12 g/dl for male patients and >10 and < or =11 g/dl for female patients), while 8.5% had severe anaemia (Hb concentrations < or =11 g/dl for male patients and < or =10 g/dl for female patients). A strong association existed between Hb concentration and renal graft function. Of the patients with a serum creatinine level >2 mg/dl (which indicates impaired kidney function), 60.1% were anaemic, compared with 29.0% of those with a serum creatinine level < or =2 mg/dl (P<0.01). Other risk factors for anaemia include therapy with angiotensin-converting enzyme inhibitors or angiotensin II receptor antagonists, the use of azathioprine or mycophenolate mofetil, kidneys from older donors and recent infections. Furthermore, only 18.8% of patients with severe anaemia were treated with erythropoietic therapy. The findings from the TRESAM survey are in agreement with the results from another recently published study that included 128 renal transplant patients from two centres in the USA, who were followed for 5 years after transplantation. It was found that 30% of patients were anaemic at some point after transplantation. The prevalence increased with time after transplantation, with 26% of patients being anaemic 5 years' post-transplant. A multivariate logistic regression model identified three risk factors for post-transplant anaemia: serum total CO(2), blood urea nitrogen and creatinine. There is an unexpectedly high incidence of anaemia in patients with a functioning renal transplant: around one-third of these patients are anaemic. Most of the evidence suggests that impaired erythropoietin production by the renal allograft is the most important pathogenic factor of post-transplant anaemia. Whether this high incidence of anaemia may be an additional cardiovascular risk factor in renal transplant patients remains to be proven. However, there does not appear to be any reason why anaemic renal transplant recipients should not be treated like any other patients with renal anaemia.