Abstract:In a randomised, double‐blind cross‐over study, objective measures were used to compare the effect of a single oral dose of a standard preparation of levodopa‐benserazide (Madopar M) with a sustained‐release preparation (Madopar HBS) in 9 Parkinsonian patients with ‘end of dose deterioration’. The response of patients to an optimised regimen of each preparation was also assessed using a patient diary.In all patients the onset of effect of Madopar HBS following a single dose was delayed compared with Madopar M. The duration of effect of a single dose of Madopar HBS was substantially (38‐120%) longer than Madopar M in five patients and the same or shorter in four patients. According to the patients diaries, six patients noted an increase in ‘on’ hours while on Madopar HBS. The duration and severity of dyskinesia was similar for the two preparations.Madopar HBS is likely to be useful in some Parkinsonian patients with ‘end of dose deterioration’. As the effect of each dose is delayed it is probably best given in combination