During the course of some anthelmintic tests carried out during June, 1949, it was necessary continuously to feed 4 per cent, phenothiazine to pheasant poults in the daily mash, which they ate without any obvious distaste and grew reasonably well. The birds were a mixture of several varieties of Phasianus colchicus, including some Formosan and Korean hybrids. These latter birds have a light coloured plumage and it was soon noticed that the feathers were darkening. The change was obvious less than 86 hours after the first experimental feeding. All the birds were therefore examined and it was found that all were similarly affected though it was less obvious among the melanistics and blacknecks, which have a darker plumage. The leg scales too had taken on a distinct dark green hue, and this became more intense as the tests proceeded; the pigmented feathers assumed a fiat brownish colour, while the filoplumes are distinctly red.