Detection and investigation of all cases of acute flaccid paralysis (AFP) in children below 15 years of age are among the criteria for poliomyelitis-free certification. In the absence of poliomyelitis the incidence of AFP is around 1 per 100,000 children aged < 15 years. In the Netherlands, surveillance of AFP began in October 1992 under the supervision of the Dutch Paediatric Surveillance System (NSCK). Over 90% of clinically active paediatricians participated in the monthly reporting of new cases of AFP. From October 1992 to December 1994 (27 months), 52 cases of AFP were reported. The incidence was 0.7 per 100,000 over the period, and reported cases were evenly distributed throughout the country. The main cause of AFP was Guillain-Barré syndrome. The average time between onset of symptoms and visiting a doctor was less than 3 days. The median reporting delay was 29 days, although the system was not intended as surveillance for action. Virological examination of faeces was carried out for only 40.4% of AFP patients. The start of the NSCK surveillance system coincided with the 1992-93 outbreak of poliomyelitis in the Netherlands, but only 7 of the 18 children with paralytic poliomyelitis were reported through the AFP surveillance system. For certification purposes, the present AFP surveillance system in the Netherlands needs to be improved with respect to coverage by including neurologists, rapidity of reporting, and completeness of laboratory investigations.