The electron impact induced fragmentations of m-and p-substituted phenylacetamides and N,N-dimethyl-phenylacetamides 1-14 were investigated and compared with the o-analogues. All m-and p-substituted amides yield molecular ions with high relative intensities which do not lose their meta-and para-substituents. Loss of HNCO from M+. is dominant in the prim. amides, whilst for the tert. amides the classical benzyl cleavage is the most favourable fragmentation pathway. We have previously reported on the fragmentations of ortho-substituted phenylacetamides,) and phenylacetate~~) after electron impact. Of the ortho-substituted phenylacetamides studied (substituent X = CI, Br, F, NO,, OCH,, CH,, and CN) only the 0-0, o-Br-, and o-NO,-amides lose the ortho substituents directly from their M+. giving rise to large (M-'XPsignals, and do not yield detectable M+'(