Dosing schedules may be one important factor determining whether patients take their prescribed medication. Schedules may influence whether a patient stays on the prescribed therapy and, if so, the degree to which the regimen is followed. Both factors are important determinants of health outcomes and health care costs. The goal of this study was to investigate the impact of reducing dose frequency on health outcomes and health care costs. Articles from peer-reviewed journals were identified from the medical literature databases MEDLINE, International Pharmaceutical Abstracts, and HealthSTAR for the years 1985 through 2002. The search included all references that reported on the impact of a change of dose frequency on chronic disease. Search terms used were combinations of dose frequency, dose schedule, and dosing and efficacy, safety, clinical effectiveness, preferences, adherence, compliance, persistence, health-related quality of life, patient satisfaction, resource use, and costs. Reducing the number of daily doses through extended-release formulations or newer drugs has frequently been shown to provide the patient with better symptom control in a number of disease states. Overall improvements were seen in adherence, patient quality of life, patient satisfaction, and costs. However, results of some studies indicate that not all patients, medications, or diseases may be candidates for reduced dosing due to the potential effects on symptom control, incidence of adverse events, and overcompensation for missed doses. Where feasible, reducing dose frequency may offer benefits for the patient in terms of health outcomes and for the health care budget holder in terms of costs.