Background: The clinical and radiological evaluation of endotracheal suctioning (ETS), which is performed as a blind procedure has incapacities. The purpose of this study was to indicate that angulation of the ETT tube tip to both lung sides is an important factor in the progression and orientation of the ETSC in the bronchial system. Method: The five sheep lung was dissected to reveal bronchial system. anesthesiologist inserted the catheter into the endotracheal tube at neutral tube tip position. Then tube tip was rotated 30__ampersandsignordm; and 45__ampersandsignordm; to the right and 30__ampersandsignordm; and 45__ampersandsignordm; to the left respectively. The advancement and orientation of ETSC in the tracheobronchial system were dynamically observed with 625 insertion done by 5 different anesthesiologists. Results: The sheep tracheobronchial system can be used as a model in morphological studies. The known access limitations of an ETSC were documented in the animal model by dynamically observing the advancement and orientation of an ETSC. Conclusion: It can be entered both bronchial systems by obtaining a least 30__ampersandsigndeg; of angle to ETT tip position towards each lung side.