A granular flame retardant additive is provided comprising from 70 to 99.5% by weight of an organohalide flame retardant and from 0.5 to 30% by weight of thermoplastic synthetic resin as a binder. The additive is easy to handle and resistant to disintegration during transportation and mixing with fabricating resin pellets. Uniform distribution thereof in fabricated thermoplastic articles is achieved by simply co-feeding the granules and the fabricating resin to a fabricating machine.