Background: E-cigarette use is rapidly increasing among US young adults, heightening their risk for vaping-related illnesses. Yet, little is known about e-cigarette use among young adult Native Hawaiians and Pacific Islanders (NHPI): an indigenous-colonized US racial group rarely described in research literature. This exploratory study provides the first known data on e-cigarette use and potential risk factors in NHPI young adults. Method: Self-report data were collected from 143 NHPI young adults (age 18-30 years) living in two large NHPI communities: Samoans in urban Los Angeles County and Marshallese in rural Arkansas. We assessed rates of e-cigarette, cigarette, alcohol, and marijuana use, and positive and negative outcome expectancies from e-cigarettes, that is expected outcomes from e-cigarette use. To identify potential risk factors for NHPI e-cigarette use, regressions explored associations between participants' current e-cigarette use with current cigarette, alcohol, and marijuana use, and e-cigarette outcome expectancies. Results: Among NHPI young adults, lifetime e-cigarette use rate was 53% and current use rate was 39%. Current rate of dual e-cigarette/cigarette, e-cigarette/alcohol, and e-cigarette/marijuana use was 38%, 35%, and 25%, respectively. In our regression models, current marijuana use and positive e-cigarette outcome expectancies were significantly associated with current e-cigarette use. Conclusions: E-cigarette use is common among NHPI young adults, exceeding rates for other at-risk racial groups. Marijuana use and positive expectations about e-cigarette use may represent potential e-cigarette use risk factors. Collectively, findings underscore the need for additional research to further explore the scope of, and risk and protective factors for, e-cigarette use in this understudied high-risk population.