1. The responses of plasma levels of C-reactive protein and serum amyloid A were assessed in two groups of malnourished children.
2. Sixty-six severely malnourished children were studied at admission. Fifty of these had clinical and/or laboratory evidence of infection. C-reactive protein was not elevated in 23 (46%) and serum amyloid A was not raised in 29 (58%) of these 50 children.
3. Surviving children (n = 62) received two doses of diphtheria-pertussis-tetanus vaccine, to which the C-reactive protein and serum amyloid A responses were measured. The first was given early in recovery, the second after nutritional rehabilitation. Ten mildly malnourished children acted as controls, receiving a single dose of diphtheria-pertussis-tetanus vaccine.
4. The responses of both C-reactive protein and serum amyloid A to diphtheria-pertussis-tetanus vaccine were significantly less in early recovery than after nutritional recovery. The response of the mildly malnourished group was no different from that of the severely malnourished group in early recovery, but was less than their response on discharge.
5. The acute-phase protein response of malnourished children is impaired. This may have prognostic implications as the response plays a central role in promoting healing.