The multicenter study of hydroxyurea (MSH) in sickle-cell anemia (SCA) demonstrated that patients treated with hydroxyurea (HU) had a 44% decrease in hospitalizations when compared with those taking placebo. A subsequent study looking at the cost-effectiveness of HU showed that decreased hospitalizations for painful crisis accounted for the majority of cost savings in those taking HU. The purpose of this study was to examine whether the expected decrease in hospital utilization occurred after the approval of HU in Maryland. We used data collected by the Maryland Health Services Cost Review Commission to obtain SCA discharge data for Maryland from FY1995 through FY2003. We also reviewed the inpatient and outpatient charts of all adults with SCA admitted to a large university hospital during 2003. Hospitalization rates for adults with SCA in Maryland have increased significantly since approval of HU. While the total costs of inpatient care in Maryland are estimated to have increased by 31% above inflation from 1995 to 2003, the costs of inpatient care for adult SCA patients has increased by almost 60% above inflation. By comparison, there has been no significant increase in the pediatric hospitalization rate. We found that 70% of patients in one hospital who were appropriate candidates for HU were not taking the medication. Hospital utilization among adults with SCA has increased significantly. There are likely many factors that have played a role in this increase. One factor that appears to be involved is the underutilization of HU.