Abstract Purpose Highly unusual histologic findings at the porta hepatis in 3 infants who underwent Kasai portoenterostomy for biliary atresia are reported. Methods Portoenterostomy was performed using a standard operative technique. Serial transverse sections of the excised portal plate were examined by light microscopy along with sections from the distal extrahepatic biliary remnants, gallbladder, and liver biopsy. Results Of 61 consecutive infants who underwent Kasai portoenterostomy for biliary atresia, 3 were found to have highly unusual histologic features at the porta hepatis. All had type 3 biliary atresia. Two had hilar biliary ductules lined in part by squamous epithelium, and the third had a focus of mature hyaline cartilage surrounded by perichondrium adjacent to biliary ductules. In each case, these unusual histologic features were localized to the porta hepatis in the region of the transected portal plate. Conclusions The presence of hyaline cartilage at the portal plate is likely to be an expression of defective morphogenesis, thus supporting the concept of disordered embryogenesis in the etiology of biliary atresia. Squamous epithelium within biliary ductules might also reflect a similar mechanism but could alternatively be an unusual metaplastic response to inflammation at this site.