As Parkinson's disease worsens, many patients develop motor fluctuations which usually correlate directly or indirectly with L-dopa plasma levels. A new L-dopa-benserazide HBS preparation (Madopar) a control release pharmaceutical formulation which is activated when it contacts gastric fluid thus providing more stable L-dopa plasma levels, was assayed. Ten patients with a diagnosis of idiopathic Parkinson's disease and motor fluctuations otherwise unresponsive to conventional therapy were selected. The average age was 62 years and the duration of the disease 9 years. The motor status was evaluated on an hourly basis with the King's College Parkinson's disease rating scale; in addition, a nocturnal disability scale (Lees) was used. Out of the 10 patients, 2 dropped out within the first month due to worsening of parkinsonian signs, while 7 of the remainders preferred HBS preparation to the previous treatment. The number of off hours in this group was reduced by 58% and motor fluctuation became less severe. In only 3 cases was it possible to use HBS as monotherapy while in the rest standard L-dopa had to be added, specially as morning doses. The average L-dopa daily dose was increased by 36%. Unwanted effects included psychiatric disturbances in two (in one L-dopa dose had to be reduced) and epigastralgia in one. Our findings suggest that this L-dopa-benserazide control release may be considered an able therapeutic formulation in the control of motor fluctuations in Parkinson's disease.