Anorectal malformations include various type of anomalies resulting from abnormal development of hindgut, allantois and Müllerian duct. It is essential for the successful construction of new anorectum to know the correct anatomy of pelvic muscles. Peña and deVries proposed a new concept of pelvic muscles, the surgical entities "muscle complex". Based on new anatomical understanding, posterior sagittal anorectoplasty (PSARP) was described by Peña and deVries and has gained a wide acceptance in the world. This approach may lead us a better understanding of surgical anatomy and change our therapeutic concept. Hirschsprung's disease is known to be congenital disorder characterized by the absence of enteric nervous system. Recently, gene mutations associated with Hirschsprung's disease have been widely investigated and gene mutations of RET, glial cell line-derived neutrophic factor (GDNF), endothelin receptor B (EDNRB) and endothelin-3 (EDN3) have been identified in patients with Hirschsprung's disease. These results suggest a role of gene mutations in the migration and differentiations of neural crest-derived neuroblasts. One-stage endorectal pull-through procedure in the neonate and a primary laparoscopic pull-through procedure has been shown to be feasible.