This paper proposes two improvements in the design of unknown input observers (UIO) for linear parameter varying (LPV) systems. First, the parameter dependency of the UIO is not restricted to mimic the one of the system in order to relax the existing decoupling conditions. Second, the output equation of the LPV systems is not supposed to be linear time invariant. Both perfect Ul decoupling or mixed decoupling and attenuation are considered, whether the relaxed structural conditions are met or not. (C) 2018 Elsevier Ltd. All rights reserved.