Département de Physique, Université de Montréal, Montréal, QC, Canada, H3C 3J7

No confirmed detection of a surface magnetic field exists for any nondegenerate star earlier than about spectral type B2. On the other hand, the existence of intense fields in main sequence A and B type stars, along with the cyclic variability commonly observed in the winds and envelopes of many O and Be stars, provide strong indications that magnetic fields are indeed present in hot stars. In this paper I discuss the observational and theoretical bases for suspecting that many hot stars host surface magnetic fields of order 10-1000 G. I describe the difficulties involved in using conventional Zeeman magnetic diagnostic techniques to detect such fields, and review the various attempts to date. I conclude by describing the recent ``success stories'' of  Cep and ¹ Ori C, and describe possible future strategies and the outlook for exploitation of large telescopes.

In the proceedings of Magnetic Fields Across the H-R Diagram
Preprints from wade@astro.umontreal.ca
or on the web at http://www.astro.umontreal.ca/~wade