On 67 cases of pancreas head region cancer with its definite diagnosis confirmed by laparotomy, studies were made of their ultrasonograms and of their urtrasonic tissue characterization obtained from the ultrasonography of the resected specimens immersed in water in 17 of 29 cases resected. The following results have been obtained. Ultrasonogram of pancreas head region cancer has the following characteristics. Direct findings: i) abnormal internal echo level of tumor images, ii) irregular images of tumor margin, iii) irregular internal echo of tumor images, iv) localized enlargement of the pancreas, v) altenuation or disappearance of back echo of tumor images. Indirect findings: i) dilated common bile duct ii) enlarged gallbladder, iii) dilated intrahepatic bile duct, iv) dilated pancreatic duct, v) abnormal deformation of vascular images surrounding the pancreas. Resected cases had less scanty ultrasonographic findings than non-resected cases. The detection of pancreas head region cancer by ultrasound was possible in 43 cases (64.2%). Differential diagnosis of pancreas head region cancer by ultrasound may be possible to a certain extent. Internal echo level of tumor images had a close relation with tissue-type, interstitial connective tissue hyperplasia and the cut surface structure of the resected specimens.