Objectives: Using laryngeal endoscopy and VHI scale to diagnose and evaluate effectiveness of treatment of unilateral vocal cord paralysis with open position. Method: Clinical trial, performed at ENT Department, Nhan Dan-Gia Dinh hospital from October 2013 to October 2015. Patients were diagnosed using laryngeal endoscopy measuring glotis patent level and VHI, compared these 2 criteria at before and after surgery. Result-Discussion: 90 patients are diagnosed and injected fat into paralysed vocal cord, measured glotis patent level while pronouncing I, E. Pre-operative rate is 100 percent with average patent level of 3.9mm (1.4mm- 9.8mm). Post-operative result showed 90 percent of patients having totally closed giotis, average patent level reduces to 0.05 7mm. Pre-operative average VHI index is 65/120 points, post-operative index reduces to 21/120 points. There were 90 percent of patients have mild to moderate level. Conclusion: Using laryngeal endoscopy measuring glotis patent level while pronouncing I, E and VHI scale to diagnose and evaluate effectiveness of treatment of unilateral vocal cord paralysis with open position are 2 criteria for subjective and objective evaluation helping ENT physicians in ENT hospitals effectively.