Searches for new physics using muons are reviewed. Particular
attention is paid to muon number non-conserving processes, like the
decay $\mu\to e\gamma$ and muon–electron conversion in muonic atoms.
Also, experimental determinations and theoretical predictions for the
muon anomalous magnetic moment are reviewed.
Proceedings of the fifth conference ``Beyond the Standard Model'', May 1997, Balholm, Norway; published by the American Institute of Physics, AIP conference proceedings 415, 1997.