Some features of the problem of pipeline materials degradation and failure under in-service conditions, including environmentally assisted cracking, are examined. As the practice of cathodic protection results in hydrogen charging of carbon steels used as components of oil and natural gas transmission pipelines, close attention is paid to the role of hydrogen embrittlement (hydrogen-induced cracking) in pipeline safety and reliability. (C) 2005 Elsevier Ltd. All rights reserved.