The spectrum of NH in Comet P/Halley (W. D. Cochran 1986, In 20th ESLAB Symposium on the Exploration of Halley's Comet, ESA SP-250, Vol. 1, pp. 317–321) is shown to be due to pure fluorescence with negligible influence by collisions. The fluorescence efficiency is shown to be a factor 5 lower than previously calculated. The absence of collisions may indicate that the NH exists predominantly further from the nucleus than 30,000 km and that it is therefore not a direct dissociation product of NH3 from the nucleus.