Coiled-tubing (CT) drilling is a technology of the current decade. The question that many operators have regarding CT drilling is, "Should we consider using CT drilling in our operations?" CT drilling has a considerable number of advantages over conventional drilling methods in certain applications, but it also has a number of limitations that an operator must be aware of. The decision to use CT for drilling must be based on its capabilities because conventional economics seldom favor its use as a drilling method. CT does have unique capabilities that make it excel in true under-balanced drilling and in certain re-entry applications.