Photodissociation dynamics of methacrylonitrile (H2C=C(CH3)CN) and 2-butenenitrile at 193 nm have been investigated by measuring laser induced fluorescence spectra of CN fragments. From the spectra, internal and translational energy distributions of CN have been obtained. For both molecules, the measured energy distributions are well represented by statistical prior calculations, assuming the CN and allyl radical products rather than the propenyl isomer. Ab initio calculations were performed for the relevant product species and transition states for isomerization and CN elimination. It has been concluded that methacrylonitrile dissociates in the ground electronic state via allyl cyanide formed by CN and H atom migration prior to dissociation. The quantum yield of the CN channel from methacrylonitrile was measured to be 0.012 +/-0.001.