Clogging of Continuous Casting nozzle has a detrimental effect on productivity and product quality; it also increases production costs and goes against security. Many factors contribute to the clogging phenomenon, including the detailed process parameters of continuous casting and secondary metallurgy. Clogging can be effectively limited by Argon injection that is usually performed through the stopper rod. The nature and quality of the refractory equipment is another factor that must be considered carefully. The clogging mechanism has been clearly ascribed to the level and nature of non metallic inclusions, thus to the secondary metallurgy process. Effective counter measures that have been successfully implemented in Arcelor to achieve long sequence casting are presented.