YH molecules were produced by laser vaporizing yttrium in the presence of He doped with H-2 or NH3. Stark spectra were recorded for four bands in the 19300-19800 cm(-1) region at electrostatic fields up to 16 kV/cm. Stark measurements proved useful in establishing rotational and Omega quantum number assignments. The permanent electric dipole moments (in Debye) were measured to be: 1.569(64), 2.325(8), 3.316(11), 2.273(6), and 1.537(8) for the X'Sigma(+) ground state and the 19385, 19746, 19572, and 19575 cm(-1) excited states, respectively. Strong variation of the effective Omega quantum number with J was detected for the 19572 cm(-1) state. (C) 2002 Elsevier Science B.V. All rights reserved.