The aim of this study was to evaluate the effects of various glucosinolate-derived hydrolysis products (HP) as antibacterial compounds against Enterobacteriaceae and Enterococcaceae isolated from intestinal segments of healthy pigs collected directly from slaughter-houses in the North of Portugal. Using a previously described disk-diffusion bioassay, all HP were tested at six different doses (0.015, 0.15, 0.75, 1.5, 3.0, and 15.0 μmoles) in dimethyl-sulfoxide (DMSO), with the exception of sulforaphane (SFN), which was not tested at 15.0 μmoles. Positive (antibiotic standard) and negative controls (DMSO) were included in all experiments. All the experiments were conducted in triplicate. In vitro inhibition of the bacterial growth by the HP was proportional to the concentration used and in many cases was even higher than for the gentamycin, the antibiotic control. The results clearly showed that the glucosinolates-derived HPs were very effective in vitro inhibitors of bacterial growth. The natural products, and specifically the isothiocyanates, should be evaluated as potential alternative control agents for potentially pathogenic bacteria (e.g., dietary amendment of pig foods with glucosinolate-containing plants).