Pediatricians express difference of opinion as to the relative frequency of megacolon. Some authors of wide experience are able to make reports on only one or two such cases; that such experience is not general is attested by the fact that in the literature of the past four years there are more than one hundred papers each of which deals with one to six cases. It follows, therefore, that the affliction cannot be extremely rare. We have encountered six cases during the past five years; two of these passed from observation after one view and, therefore, are not included in this report. Microcolon, on the other hand, seems to be truly an unusual condition, as our search through the literature revealed but three certain and one doubtful case, although it seems probable that some reports under the caption "Stenosis of the Colon" may have referred to this condition.