This study is designed to evaluate results of ultrasound guided internal jugular vein catheterization in emergency ward and promotion of its using in Iran. One hundred patients referred to emergency ward of Baqiyatallah Hospital needing internal jugular vein catheterization will randomly assigned to two groups. Catheterization will be accomplished using ultrasound guidance after viewing internal jugular vein in the first group, and using anatomical landmarks in the second group. Patients younger than 14 years old and pregnant women will be exclude from study. Side of catheterization (left or right), risk factors such as hypertension, diabetes mellitus, coagulopathies, ischemic heart disease, cigarette smoking, edema, local masses, shock, cardiac arrest, chronic lung diseases, loss of consciousness, sepsis, malignancy, renal disease, trauma, hepatic failure, hematologic disorders, electrolyte imbalance, respiratory distress, patients under mechanical ventilator and vasodilator drugs infusion will be evaluated. Venous access time, numbers of tries, success rate, and catheter related complications will be compared between groups.