Introduction: The purpose of this study was to investigate the Reliability of 3-D scapular kinematics measures of Motion analyzer and Acromion cluster in patients with Shoulder impingement syndrome during humeral elevation and lowering.Material & Methods: 20 Patients (Males=13, Females=7) with Shoulder Impingement Syndrome (mean age: 46.15 years) who participated in the study. They elevated and lowered humerous in frontal, sagittal and scapular movement plane during 8 seconds, using the VICON motion analyzer and Acromion marker cluster. The Scapular 3-D kinematics was measured, using VICON motion analyzer and Acromion marker cluster. Interclass correlation coefficient and Standard error of measurement were used.Results: Participants showed average of age 46.53±13.314 as well as average of BMI 28.14±3.93, and all quantitative and qualitative variables had the normal distribution. Trial-to-trial ICCs for the 3-D scapular kinematics variables for both elevation and lowering condition in the sagittal, frontal and scapular planes ranged from 0.58 to 0.99, which indicated fair to excellent reliability, and the SEM for both elevation conditions ranged from 1.7 to 15.4 .Discussion: The reliability of the three-dimensional scapular attitudes for elevation and lowering phases were very good. The estimation of three-dimensional scapular attitudes using the method of calculation relative to the trunk is reproducible in the three movement planes during elevation and lowering phases and can be used to document the scapular behavior.