We examined the effects of research handling on free-ranging endangered Hawaiian monk seals, Monachus schauinslandi, by analyzing differences in subsequent year survival, migration, and condition between handled seals and controls during 1983–1998. Each of 549 handled seals was matched to a control seal of the same age, sex, location, and year. Handling included instrumentation with tel metry devices (n= 93), blood sampling (n= 19), and tagging (n= 437). No significant differences were found between handled seals and their controls in one-year resighting rates, observed migration rates, or condition. Resighting rates of handled and control seals were high (80%-100%). Available sample sizes were sufficient to detect reasonably small (9%-20%) differences in resighting rates had they existed among instrumented or tagged seals and controls (α= 0.05, power = 0.90). Too few seals were captured for blood sampling to detect even large differences in their resighting rates. However, blood samples were drawn from most instrumented seals, and there was no indication that this larger group suffered harmful effects. Duration of restraint during flipper tagging had no effect on subsequent probability of resighting. Our analysis suggests that conservative selection procedures and careful handling techniques have no deleterious effects on Hawaiian monk seals.