The pharmacokinetic advantage of controlled-release carbidopa-levodopa (Sinemet CR) is its slow dissolution and gradual absorption, resulting in more sustained plasma levodopa levels and higher plasma troughs. In patients with moderately severe disease, the benefits include less severe "wearing-off," a modest increase in daily "on" time, and fewer daily doses. Bioavailability of Sinemet CR levodopa is less than that of standard Sinemet, so a slightly higher total daily levodopa dose is required to achieve a comparable effect; but because Sinemet CR is absorbed much more slowly than is the standard preparation, dosing frequency can be reduced by up to half. For most patients, titration will be required after the transition has been made from standard to controlled-release Sinemet. The effect of Sinemet CR on dyskinesias is often difficult to predict and, in individual patients, may depend on the temporal pattern of dyskinesias being experienced. Success in using this new preparation depends on understanding its pharmacokinetic properties, judicious patient selection, and an effective program of patient education.