Since the inception of deep water operations, drilling riser seal component failures have been a persistent problem worldwide. Traditionally these failures have required that the drilling riser be pulled, the affected seals replaced and then the drilling riser re-installed; resulting in substantial rig down time and expense to the operators and service companies. Seal-Tite International has developed a unique array of pressure activated sealants able to withstand the high pressure and extreme temperature conditions associated with subsea drilling and production operations. The sealant is polymerized by the differential pressure created through the leak sight. The polymerization process only occurs in the sealant that passes through the leak sight; all other sealant remains liquid and can be circulated out of the well with no damage to any of the well components. Subsequent to extensive testing, pressure activated sealant technology was utilized to repair a leaking joint in a drilling riser choke line at approximately 4200 ft water depth in the Gulf of Mexico. The leak was repaired and the client was able to continue and complete drilling operations with no downtime. The riser was tested to operating pressure every three days for the duration of the drilling operation with no leaks observed.