The authors used the 1992-1995 National Health Interview Survey to examine the effect of immigrant status (both nativity and duration of residence in the United States) on the health of Asian and Pacific Islander adults by constructing models in which national origin was also specified. In logistic regression models adjusted for age, marital status, living arrangement, family size, and several socioeconomic indicators, immigrants were found to be in better health than their US-born counterparts, but their health advantages consistently decreased with duration of residence. For example, for Asian and Pacific Islander immigrants whose duration of residence was less than 5 years, 5-9 years, and 10 years or more, the odds ratios for activity limitations were 0.45 (95% confidence interval (CI): 0.33, 0.62), 0.65 (95% CI: 0.46, 0.93), and 0.73 (95% CI: 0.60, 0.90), respectively. Similar findings emerged for respondent-reported health and bed days due to illness. These results support the validity and complementarity of the migration selectivity and acculturation hypotheses. However, the picture was not uniformly positive. The health of certain Asian and Pacific Islander groups, notably Pacific Islanders and Vietnamese, was found to be less favorable than average. Finally, after adjustment for health status, immigrants seemed to have less adequate access to formal medical care.