  We show analytically that large abundances of NH2D and NHD2 can be produced
by gas phase chemistry in the interiors of cold dense clouds. The calculated
fractionation ratios are in good agreement with the values that have been
previously determined in L134N and suggest that triply-deuterated ammonia could
be detectable in dark clouds. Grain surface reactions may lead to similar NH2D
and NHD2 enhancements but, we argue, are unlikely to contribute to the
deuteration observed in L134N.
