Silver staining is a useful means of demonstrating enteric neurons, and an absence of argyrophilic neurons has been proposed as a cause of functional intestinal obstruction in infants. No systematic data are available about the origin and development of argyrophilia, or of normal neuronal appearances. Specimens of colon from 48 infants and children (pre-term to 14 years) who had died of nongastrointestinal causes were studied by silver staining. Inter-sample variations in neuronal size, morphology and intensity of staining (strong, faint or absent) were seen: strong argyrophilia (n = 17), age range three days to eight years (median seven months); no argyrophilia (n = 19), pre-term to one year (median eight weeks); weak argyrophilia (n = 12) one day to 14 years (median eight weeks). Neurons in every preterm infant were argyrophobic, and argyrophilic neurons were always found in babies aged over one year. Where argyrophilic neurons were seen, argyrophobes outnumbered them (median ratio of 9:1). This study demonstrated considerable variability in the appearance and argyrophilia of colonic myenteric neurons in the first year of life. The data were consistent with the continuing post-natal development of the enteric nervous system in a manner analogous to the brain, and show the importance of age in the interpretation of silver-stained material from infants with pseudo-obstruction.