Searches for SUSY Particles at HERA

Searches at the e-p collider HERA for supersymmetric partners of the Standard Model fermions are presented. Assuming R-parity conservation, selectrons and squarks of the Minimal Supersymmetric Standard Model are excluded for masses up to 65 GeV in a new region of the standard parameter space. Admitting in addition a R-parity violating Yukawa coupling $\lambda'$, squarks are sought through direct e-q fusion in a yet unexplored mass-coupling domain, taking into account all possible squark decays. Squark masses up to 240 GeV are excluded for $\lambda' \gtrsim \sqrt{4 \pi \alpha_{em}}$, depending only weakly on the free model parameters.