We have used a continuous perfusion probe for manometry in newborns. We carried out 95 pressure recordings in 56 patients labeled as delayed passage of meconium longer than 24 h. When the relaxation reflex of the anal canal was not present after rectal stimulation with a distensible balloon, the tests were repeated weekly up to the first month of life. Thereafter, suction biopsies were carried out to confirm the final Hirschsprung's disease (HD) diagnosis. The amplitudes of the fluctuating waves in HD subjects were higher than those in non-HD patients. Although the procedure could provide false positive results, no possibilities exist for false negative results as proved in our study. All the five cases with HD were diagnosed by our manometric procedure as well as by histochemistry. The method is advantageous and profitable for the diagnosis of HD in case of delayed passage of meconium or distal functional obstruction of the anal canal.