One year after immunization with a single 0.5-mL dose of influenza virus vaccine, serum samples from 30 children with renal diseases were tested for serum hemagglutination-inhibiting (HI) antibody titers to A/New Jersey/76, A/Victoria/75, and A/USSR/77. Eleven unvaccinated children with renal diseases formed a comparison group. In contrast to the comparison group (0/11), 53% (16/30) of the vaccinated group had a protective level of serum HI titers (greater than or equal 1:40) against A/New Jersey. A protective level of serum HI titer against A/Victoria was noted in 83% (25/30) of the vaccinated group, while 54% (6/11) of the unvaccinated group had similar HI titers. None had a detectable HI titer against A/USSR. A minor common cold-like illness occurred in seven of the 30 vaccinated children; one of these had exacerbation of nephrotic syndrome. The data suggest a good protection against influenza one year after vaccination in children with renal disease.