Ii have been interested in the discussions about atenolol with Sinemet. About two years ago I had a spell of cardiac arrythmia which was diagnosed as annoyiang but not serious. It was most annoying, however. I was put on atenolol and have stayed on that drug since. Then along came PD with it's problems, and I was put on Sinemet RC. In retrospect the next day I had a recurrence of my cardiac arrythmia. At first I did not connect the two and kept on trying to adjust the dose od Sinemet. Finally I got frustrated at the intestinal complaints that I was getting, so stopped the Sinemet. Within two days the cardiac arrhythmia stopped. Just for a trial I took one half tablet of Sinemet once a day, and within 12 hours my cardiac symptoms recurred. Stopped the Sinemet, they stopped. I have done this three times, and each time the irregular heart beat occurrerd as soon as I took even the smallest dose of Sinemet. It may be that whatever the cardiac condition is is what makes he incompatability of the two drugs, but I was interested to see that there is someone else out there who has noticed the relationship. I am now off of Sinemet and feel better without it. Don Stokes