There has been much debate over the merits of consumer-directed health plans (CDHPs), yet there is little empirical evidence of their influence on health care use. We examined patterns in prescription drug use in the first year that CDHPs were offered alongside traditional plans. Using pharmacy claims data from one large company, we found that enrollees in high-deductible CDHPs were much more likely than those with other coverage to discontinue two of five drug classes. Enrollment in a CDHP did not, however, reduce adherence among those continuing their medication, nor did it greatly influence the use of generic drugs.