Subsea pipelines are subjected to external damage by fishing trawlers or dragged anchors which may result in a pipe defect such as a puncture, dent, gouge, crack or a combination of such defects (Allouti et al., 2014). Therefore, evaluation of these defects is very important in terms of assessment and for continued safe operation. This study is to evaluate the effect of dent with crack defects on the fatigue life of natural gas transmission pipelines. In order to illustrate the effect of a crack on the dented pipe, this study is divided into two parts. The first part is to study on the effect of dents alone on the fatigue life of the material, while the second part is to study on the effect of dents and crack on the fatigue life. Therefore, a parametric study using finite element numerical models was conducted to study the effect of plain dent and dent with crack on the fatigue life of the pipeline.