The collections are held each year in an effort to prevent dangerous chemicals from damaging the environment.
Five collections are scheduled in all. The first two take place Saturday in Dennis and Wellfleet.
Residents can drop unwanted hazardous material at the Tony Kent Arena from 9 a.m. to 1 p.m. in Dennis.
In Wellfleet, the material can be dropped at the transfer station from 9 a.m. to noon.
Other towns have scheduled collections throughout the summer and fall.