In the US, sexual and gender minority populations are disproportionately affected by HIV. Pre-exposure prophylaxis (PrEP) is a key prevention method, but its effectiveness relies on consistent usage. Our four-year national cohort study explored PrEP discontinuation among sexual and gender minority people who initiated PrEP. We found a high annual rate of discontinuation (35-40 percent) after PrEP initiation. Multivariable analysis with 6,410 person-years identified housing instability and prior history of PrEP discontinuation as predictors of discontinuation. Conversely, older age, clinical indication for PrEP, and having health insurance were associated with ongoing PrEP use. To promote sustained PrEP use, strategies should focus on supporting those at high risk for discontinuation, such as younger people, those without stable housing or health insurance, and prior PrEP discontinuers.