Searches for New Particles

\begin{abstract} Searches for Standard Model and Supersymmetric Higgs, supersymmetric particles and leptoquark at HERA, LEP and TEVATRON colliders are reviewed. No evidence for a positive signal is seen, but significant and constraining limits are placed. In particular the Standard Model Higgs boson must be heavier than 77.5 GeV and the lightest neutralino heavier than 14.0 GeV for all $\tan\beta$ and all sneutrino masses. A lower limit on the mass of a first generation scalar leptoquark of 225 GeV at 95\% C.L. has also been obtained. \end{abstract}