Process for gas phase polymerization of olefins

Novel gas phase fluidized bed process for producing ethylene polymers having improved processability. Multiple reactors in series or parallel may be used to produce in-situ blended polymers. Each reactor can separately have a constrained geometry catalyst or a conventional Ziegler-Natta catalyst as needed for obtaining in-situ blended polymer with the desired properties as long as there is a constrained geometry catalyst in at least one reactor. Olefin polymers can be produced according to this invention having low susceptibility to melt fracture, even under high shear stress conditions.