The extreme, possible symbiotic Mira V407 CYG and its relevance to the OH/IR sources.

Optical and IR magnitudes and photometric data on V 407 Cyg are reviewed, including new high- and low-resolution optical spectra. The nature of V 407 Cyg is examined, suggesting a classification as a symbiotic star. The spectral energy distribution, B light curve, dust obscuration events, orbital period, and accretion rates of V 407 Cyg are discussed. An orbital period of 43 yr is found for the Mira variable and wind accretion paramaters on the probable white dwarf companion are estimated. The implications of the results for studying OH/IR sources are considered.