ABSTRACT: Wire arc additive manufacturing (WAAM) process, which depends on conventional welding arc processes, is a promising option for industries when compared to typical manufacturing processes for assembling large and complicated products. WAAM process attracting manufacturing industries due to its potential to make large and complicated components with real sharp production run time with almost single step process. The process represents greater material savings, higher material buildup rate and speed, cost savings, lower cycle time, less impact on the environment, and capability of producing large size parts when evaluated with other fabrication methods. This paper focuses on WAAM process and reviews some of the common possible process defects found in variety of studies made previously to summaries a guideline for the causes of such defects and provides some prevention methods found by those studies. Of these common possible defects found in researchers works and reviewed in this work are pores, lack of fusion, cracks, and residual stress.