In this study, a 17-4 PH precipitation hardening stainless steel propeller shaft failed in use when installed in a sail-boat working in a marine environment. Failure analysis was conducted on the propeller shaft. Results indicate that the failure was caused by the fracture of the propeller shaft by torsional fatigue and stress corrosion cracking (SCC). SCC progressed transgranulary in the martensitic matrix. (C) 2003 Elsevier Ltd. All rights reserved.