In order to clarify the mechanism of the abnormal Fischer indolization of 2-methoxyphenylhydrazones the Fischer indolization of ethly pyruvate 2-(2, 6-dimethoxyphenyl)phenylhydrazone (6) was undertaken using ethanolic hydrogen chloride and zinc chloride as an acid catalyst. The cyclization was found to take place predominantly on the 2, 6-dimethoxyphenyl nucleus to give the corresponding indoles, although the yields of indoles formed were low. Some non-indolic by-products were also produced which might give information about the mechanism of Fischer indolization. In particular, the formation of 3, 5-dimethoxy-4-anilinobenzaldehyde (15) suggests that the first cyclization step in Fischer indolization could take place at the para position of phenylhydrazone as a side reaction.