Although the percentage of overall AIDS diagnoses remains low among Asian and Pacific Islanders (APIs) in the United States compared with other racial/ethnic groups, research on API risk behaviors and health status suggest that the low number of AIDS cases may not provide a full picture of the epidemic and issues faced by this understudied and underserved population. Data from national HIV/AIDS surveillance systems and the Behavioral Risk Factor Surveillance System (BRFSS) were examined to delineate the magnitude and course of the HIV/AIDS epidemic among APIs in the United States. Same-sex sexual activity is the main HIV risk for API men, whereas heterosexual contact is for API women. APIs are significantly less likely to report being tested for HIV despite the fact that a similar proportion of APIs and other racial/ethnic groups reported having HIV risk in the past 12 months. Given the enormous diversity among APIs in the United States it is important to collect detailed demographic information to improve race/ethnicity and HIV risk classification, conduct better behavioral and disease monitoring for informing prevention planning, and addressing cultural, linguistic, economic and legal barriers to HIV prevention among APIs.