I use seroquel (quetiapine) 300 mg pr. Day. My resting pulse is often above 100. I'm quite tall and have normal blood pressure and work out. Norm. Weight. Wtd?

Common side effect. I suggest, if you are otherwise healthy, that you try and make sure you are drinking plenty of fluids, water is best. I bet that will help. Also, remember seroquel (quetiapine) may cause weight gain, so watch out for that. Finally, be sure to discuss this with the dr. Who prescribed the medication.
Call your doctor. Seroquel (quetiapine) has a number of side effects some of which can be quite severe. It can cause slow, rapid or irregular heart beats and that is considered a serious side effect that requires medical attention as soon as possible. Because you are tall and have intermittent rapid pulse surges you might consider being evaluated for Marfan syndrome as well, although folks who have marfan's are usually thin.