(1) Objectives, The aim of this study is comparison of semi-surgical percutaneous dilatational tracheostomy (SSPDT) With method of conventional percutaneous dilatational tracheostomy (PDT). (2) Design, In a randomized clinical trial after approval of the ethics committee of the Babol University of Medical Sciences, 160 hospitalized patients in the ICU of rhohani hospital, babol, who needed tracheostomy were enrolled to two equal groups of PDT and SSPDT. (3) Setting and conduct, after taking written consent about type of surgery, all patients receive midazolam 0.05 mg/kg, fentanil 2µg/kg. In conventional PDTgroup the needle is inserted blindly into the trachea and a Seldinger-type guide wire (Ciaglia Blue Rhino method) is placed into the lumen of the trachea. The stoma is then created by passing single dilators over the wire and a guiding catheter. In SSPDT group dissection (1.5 cm horizontal) is high in the neck 1cm below the cricoid cartilage to visualize easier and more convenient access to the trachea from the skin surface (4) Inclusion criteria: All patients requiring tracheal intubation for more than 14 days.Exclusion criteria: emergency tracheostomy, anterior cervical infection, enlargement of the thyroid gland; coagulation disorders, age younger than 18. (5) Intervention, In SSPDT group dissection (1.5 cm horizontal) is high in the neck 1cm below the cricoid cartilage.(6) Main outcome measures (variables), duration of receiving mechanical ventilation and ICU stay, complications of tracheostomy including bleeding, pneumothorax, stomal infection and accidental decannulation