We study the effects of dielectric screening on the scattering and relaxation rates due to electron-phonon interactions in quasi-one-dimensional quantum-well wires. Interaction of confined electrons with bulk polar-optical and acoustic phonons are considered. Acoustic phonons are examined both in the deformation potential and the piezoelectric couplings. Screening effects are included via a temperature dependent dielectric function T(q) in the random-phase approximation, by renormalizing the electron-phonon interaction. We report numerical results for the GaAs system in the size quantum limit, where the lowering of screened electron-phonon scattering rates is found. The effects of screening are most significant for the electronoptical-phonon interaction. Mobility calculations using the screened electron-phonon interactions are also considered. © 1993 The American Physical Society.