The electrical and electroluminescent (EL) properties of poly(p-phenylene vinylene) (PPV) Langmuir-Blodgett (LB) film based light emitting diodes, i.e. ITO/PPV/Al and ITO/HTL/PPV/Al devices, were investigated, and found to depend strongly on the thickness of the PPV LB film. The electrical conductivity of the PPV LB film was in the range of 10(-12) to 10(-15) S cm(-1). Under a forward bias, the light emission reached more than 100 ed m(-2) in an ITO/PPV(80L)/Al device. Since the EL spectrum was similar to the photoluminescent (PL) spectrum, it was concluded that EL resulted from the recombination of injected charges in the PPV layer.