Clogging of Continuous Casting nozzle has a detrimental effecton productivity and product quality; it also increases productioncosts and goes against security. Many factors contribute to theclogging phenomenon, including the detailed process parametersof continuous casting and secondary metallurgy. Clogging can be effectively limited by Argon injection that isusually performed through the stopper rod. The nature andquality of the refractory equipment is another factor that must beconsidered carefully. The clogging mechanism has been clearlyascribed to the level and nature of non metallic inclusions, thus tothe secondary metallurgy process. Effective counter measures that have been successfullyimplemented in Arcelor to achieve long sequence casting arepresented.