The rising availability through the Internet of commonly abused prescription drugs has raised public health concerns. We examined whether the growth of US prescription drug abuse may be explained by the parallel growth in high-speed Internet use. We find that for every 10 percent increase in high-speed Internet use at the state level, associated treatment facility admissions for prescription drug abuse rose by 1 percent. Admissions for abuse of alcohol, cocaine, and heroin, which are not readily purchased online, had minimal or negative growth during the same period. The results suggest that better surveillance of online prescription drug sales is warranted, and aggressive efforts to curb illegitimate online pharmacies may be necessary.