Introduction: Hirschsprung's Disease (DH), also known as Congenital Megacolon, has been described as a congenital disorder in Newborns (NB) with severe constipation associated with dilatation and hypertrophy of the colon. To elucidate the diagnosis, it is necessary to perform complementary tests, but the gold standard is rectal biopsy. The treatment is always surgical, aiming at the removal of the aganglionic part and the restoration of the continuity of the intestine. Thus, we chose to report a case of a 1-year and 10-monthold patient with chronic constipation from birth, who was diagnosed with DH, requiring surgical intervention. Case report: A 29 days of life male patient comes with a complaint that he has been evacuating in small quantities since birth, with feces that look yellowish, pasty and with a characteristic odor, intercalating with periods of constipation. Mother reports that the RN remained for up to a week without evacuating from birth. With the DH hypothesis, an x-ray of the abdomen, an opaque enema, and a rectal biopsy were performed confirming the hypothesis. We opted for surgical treatment where initially a colostomy was performed on a loop and then a rectosigmoidectomy with colon retraction. Discussion: HD is a congenital anomaly that affects 1 in 5,000 live births. It is characterized by the absence of ganglion cells, and 80 to 90% of the cases are diagnosed in the neonatal period. The delay between the onset of clinical manifestations and the investigation of the disease increases the risk of complications, with more frequent enterocolitis, in addition to increasing the morbimortality of the congenital megacolon. Conclusion: With the present study, we aimed to emphasize the need to alert the pediatrician to a better understanding of the clinical picture of HD, as well as its complications and the importance of performing the diagnosis early