This work presents a systematic procedure to identify as well as to analyze major casting defects. Defects are responsible for time waste, money and eventually they affect productivity adversely. The defects need to be diagnosed correctly for appropriate remedial measures; otherwise, a new defect may get introduced. The proper classification and identification of a particular defect is the basic need to correct and control the quality of the casting. Keeping rejection to a bare minimum is essential to improve the yield and increase the effective capacity of the foundry unit and also improve productivity. Casting defect can negatively impact the bottom line of a foundry. A defect in a casting deteriorates casting surface quality and mechanical properties. It is responsible for loss of profitability, quality level and productivity of component. So it is preferably necessary to reduce it as much as possible by appropriate analysis. The present work is carried out in the foundry to minimize casting rejection due to a major defect. Quality analysis is carried out which includes the Root cause analysis to find out actual reasons behind occurring the blowholes. Quality control tools such as Pareto analysis, Cause, and Effect (Ishikawa) diagram, and Why-why analysis are used for analysis. Accordingly corrective actions and preventive measures are suggested and implemented.