A questionnaire was made of 130 building engineers and 35 civil engineers in Baghdad governorate to determine the quantities in construction work. Effectiveness of QMS variables in project performance was tested with regression analysis. Project performance was broken down into seven variables including Cost Variance (CV), Cost Performance Index (CPI), Time Variance (TV), Non-Conformance Report (NCR), Client Satisfaction (CS), Number of Accidents (NA) and Fatalities (F). Regression quantified the effectiveness of QMS variables in project performance. At the same time, regression explored a pattern of relationship of QMS variables to every project performance indicator. QMS variables illustrate a significant positive impact on client satisfaction and time variance. At the same time, QMS variables also show a significant negative impact on the number of accidents and fatalities.