Intensive clinical investigations on Somatostatin have been being carried out in recent years. Somatostatin and its synthetic analogues were initially used in the treatment of endocrine tumors. Today, they are being studied in the treatment of gastrointestinal diseases and successful results are being obtained.20 chronic liver disease (CLD) patients (10 chronic active hepatitis (CAH) and 10 cirrhosis), and 10 controls were included in this study. Effects of Octreotide on portal venous flow velocity were investigated using Pulsed Doppler technique. All the patients were given 100 meg Octreotide (SC), after the determination of baseline values of blood pressure; pulse rate; blood glucose, urea, creatinin, Na, K and portal venous flow velocity. These criteria were determined again in the 15, 30, 45, 60, 120 and 180th minutes after the injection.In the patients with CAH, portal venous flow velocity was changed from 11.8+2.6 cm/sec. to 9.9+2.5 cm/sec. in the 15th min. (p<0.01); to 8.7+1.9cm/sec. in the 30th min. (p<0.01); to 8.6+2.1cm/sec. in the 45th min. (p<0.01); to 8.7+2.0cm/sec. in the 60th min. (p<0.01); to 9.0+2.2cm/sec. in the 120th min. (p<0.05); and to 9.1+2.3 cm/sec. in the180th min. (p<0.05). In the cirrhotic patients and in controls, portal venous flow velocity showed similar changes and we observed that the efficacy of the drug continued until the 180 th minute.The results of this study revealed that Octreotide had caused reduction in portal venous flow velocity with a rate of 30-35 % in controls, and 20-25 % in patients with CLD.