Yes, I initially gained 20 lbs in 2-3 months also, then after 2 yrs finally lost 25 lbs while on Seroquel by exercise and counting calories.

Now that my dose has recently increased another 100mg I have already gained back 7 lbs, mostly because of cravings for unhealthy foods. Plus I'm not working right now, so that doesn't help things...

I still say Seroquel is one of the best antipsychotic meds though regardless of the weight gain. My Pdoc told me it's one of the best for Bipolar, other then Lithium.