I found amantadine extremely helpful when I began taking it about 6 months ago. I began with 100 mg. once a day and increased the dosage gradually until I was up to 100 mg. 3x/day. Unfortunately, it also caused constipation, and I decided that at this point (diagnosed 3 years ago, still in fairly early stage of PD) I didn't want to take one medicine to counteract the effects of another. So I cut back to once a day (in addition to eldepryl and parlodel). I miss the freedom of movement I had with amantadine, but it's a trade-off I chose. I'm sure some people would have chosen the opposite trade-off. Charlie Barasch Plainfield, VT