A comparison of the pyrolysis products from two types of polyethylenes, with different degrees of branching, in a fluidized bed reactor, both batch and continuously operated, is presented. Yields of 13 products (methane, ethane, ethylene, propane, propylene, acetylene, butane, butylene, pentane, benzene, toluene, xylenes, and styrene) were determined as functions of the operating conditions. The results are compared with the data obtained by pyrolysis in an apparatus (Pyroprobe 1000 + secondary reactor + gas chromatograph) where primary decomposition and wax cracking can be separated.