We assessed how point-of-care testing (POCT), diagnostic testing at or near the site of patient care, can optimize diagnosis, triage, and patient monitoring during disasters. We surveyed 4 primary care units (PCUs) and 10 hospitals in provinces hit hardest by the tsunami in Thailand and 22 hospitals in Katrina-affected areas. We assessed POCT, critical care testing, critical values notification, demographics, and disaster responses. Limited availability and poor organization severely limited POCT use. The tsunami impacted 48 PCUs plus island and province hospitals, which lacked adequate diagnostic instruments. Sudden overload of critical victims and transportation failures caused excessive mortality. In New Orleans, LA, flooding hindered rescue teams that could have been POCT-equipped. US sea, land, and airborne rescue brought POCT instruments closer to flooded areas. Katrina demonstrated POCT value in disaster responses. We recommend handheld POCT, airborne critical care testing, and disaster-specific mobile medical units in small-world networks worldwide.