The Samahang Operasyong Sagip (S.O.S) is a network of volunteer health workers, professionals, and students, aiming to render assistance to disaster victims through relief and medical missions.

It began as a volunteer team of health workers, professionals and students in 1988 and 1989 who assisted urban poor and worker communities in Malabon and Navotas who were victims of severe flooding. In 1990, after the terrible earthquake in Luzon, the volunteer teams were formally organized into a disaster response network in the health sector --the Samahang Operasyong Sagip, or S.O.S. In the same year, when the lahar flows from erupting Mt. Pinatubo ravaged Central Luzon, S.O.S volunteer teams assisted in the relief and medical missions to affected communities.