We evaluated patient acceptance and adverse effects when patients with Parkinson's disease (PD) stabilized on standard carbidopa-levodopa (Std-CL; Sinemet) were converted to controlled-release carbidopa-levodopa (CR-CL; Sinemet CR). The rational for the use of CR-CL is that continuous dopamine stimulation may delay the onset of motor fluctuations. Data were analyzed on 40 patients with PD who were on Std-CL and then were converted to CR-CL. Parkinsonian evaluations were done utilizing the Unified Parkinson's Disease Rating Scale (UPDRS), the Mini-Mental State Examination, and the Hamilton Depression Scale (HDS) while the patients were on Std-CL and following conversion to CR-CL. The median number of daily doses on Std-CL was four; on CR-CL it was two. The daily dose of levodopa during treatment with CR-CL was 29% higher than the dose during the treatment with Std-CL. A statistically significant difference existed in the dosages of Std-CL and CR-CL between stable PD patients and those with motor fluctuations. Statistically significant differences in scores on HDS and on items I, II, and III of UPDRS existed between Stages I–II and III–IV. The difference in adverse effects of CR-CL compared with those of Std-CL was insignificant. Forty percent of patients preferred CR-CL over Std-CL; 37.5% had no preference. Selection of the initial dosage of CR-CL is an important factor in therapeutic management of parkinsonism. The initial dose of CR-CL should be equivalent to 130% of the Std-CL dose. The patient acceptance rate of conversion to CR-CL was high.