This is a first report on the chain transfer behaviour of polysulfide polymers, namely poly(styrene disulfide) (PSD) and poly(styrene tetrasulfide) (PST), in the radical polymerization of styrene. It was observed that while PSD acts as a conventional chain transfer agent, PST acts as a retardant. Comparison of the chain transfer constants of PSD and PST with that of the corresponding simple sulfides indicates that polysulfide polymers are better chain transfer agents.