People without spleens have an increased risk of pneumococcal and other infections. Immunisation is advised for this group of patients, but the role of prophylactic antibiotics remains unresolved. Since 1992, general practitioners in South Buckinghamshire have been encouraged to immunise all asplenic patients against infections with Streptococcus pneumoniae, Neisseria meningitidis, and Haemophilus influenzae type b (Hib). In addition, an 'alert' card, similar in principle to a medical warning bracelet, has been produced for general practitioners to issue to asplenic patients. General practitioners' clinical records of 293 asplenic patients were subsequently examined to evaluate this programme and assess the use of prophylactic antibiotics. Uptakes of 91%, 80%, and 79% were achieved for vaccines against pneumococcal, meningococcal, and Hib infections, respectively. Twenty-three per cent of patients had been advised immediately after splenectomy to take prophylactic antibiotics. Prophylaxis was advised for different periods of time, particularly in children. Thirty-four different antibiotic regimens had been recommended for adults. Clinical records suggested that 9% of patients were taking antibiotic prophylaxis at the time of the analysis. 'Alert' cards had been distributed to 88% of patients who were eligible. It is likely that most districts within the United Kingdom could set up similar immunisation and 'alert' card programmes. The wide variation in recommendations for antibiotic prophylaxis highlights the need for further research and the development of national guidelines.