The 4 x 4 matrix method for uniaxial media developed by Berreman [J. O
pt. Sec. Am. 62 (1972) 502] and by Wohler et al. [J. Opt. Sec. Am. A 5
(1988) 1554] is extended to biaxial media by making simple modificati
ons to solutions of surface normal wave vector. For uniaxial media, th
e well known analytical expressions can be directly deduced from the m
odified solutions. This 4 x 4 matrix method for biaxial media is appli
ed to demonstrate that, for viewing directions away from the principal
planes of an optically compensated bend mode liquid crystal display,
the compensation effects of a single biaxial film are generally differ
ent from those of the combination of two uniaxial films.