Although nephrotic syndrome is well known as a predisposing factor to bacterial infection in children, especially peritonitis due to Streptococcus pneumoniae, data on the incidence of infection and the effectiveness of preventative measures are limited. With particular reference to pneumococcal disease, this review summarises the available data on the pattern and incidence of invasive bacterial infection in children with nephrotic syndrome, and the level of evidence for the use of penicillin chemoprophylaxis and pneumococcal immunisation. Although data on the effectiveness of pneumococcal immunisation in children with nephrotic syndrome are limited, the safety profile of this vaccine makes the risk–benefit ratio favourable to use of the current polysaccharide vaccine in those over 2 years of age. Conjugate pneumococcal vaccines are likely to be more effective, particularly in children under 2 years of age and should be available by the year 2000. Although penicillin prophylaxis against pneumococcal infection is not of proven benefit for nephrotic syndrome, it is beneficial in sickle cell disease without appreciable risk. Subgroups of patients with nephrotic sydrome most likely to benefit from twice daily phenoxymethyl penicillin prophylaxis include children under 2 years of age, with unresponsive or frequently relapsing disease, or who have had a previous episode of pneumococcal infection.