Searches for leptoquarks and excited fermions at HERA
  Recent results on searches for new particles at the electron-proton collider HERA are reported. Based on roughly 100pb-1 of e^+p data and 16pb-1 of e^-p data per experiment, taken in the years 1994-2000, the H1 and ZEUS collaborations have derived new exclusion limits for the direct production of excited fermion states and leptoquarks. The latter are searched for in different decay channels, including lepton-flavor violating decays. The production of R_P-violating squarks followed by leptoquark-like decays to lepton and quark is studied, as are cascade decays yielding multi-jet plus lepton signatures. New limits from indirect searches are also reported. Several of the searches obtain sensitivities of the same order or exceeding those of other experiments, indicating the substantial discovery potential of future HERA running. 
Ulrich F. Katz (U. Erlangen-Nuremberg) (for the H1 Collaborations and   ZEUS Collaborations)