Some N-trifluoromethylsulphonyl and N-trifluoroacetylderivatives of 7-amino-2,3-polymethyleneindoles and of 7-amino-3-propylindole [(I) - (XIII)] were prepared and tested, together with corresponding aniline derivates [(XIV) - (XIX)] and with N-trifluoromethylsulphonylcyclopentylamine (XX), against formic acid induced writhings in mice. With very few exceptions, at the oral dose of 0.167 mmole/kg, they proved from 2 to 3.4 times more active than acetanilide.