Salmonella enterica is of significant concern to the food industry with respect to both public health and the costs associated with regulatory compliance and recalls. Biofilm formation represents an important mechanism by which this species persists in food-related environments. We investigated the in vitro biofilm forming capacity of 20 Salmonella enterica strains representing different subspecies (I, IIIa, IIIb, IV and VI) from a range of food-related sources. In addition the strains were characterized for the carriage of seven virulence genes and for resistance to 13 antibiotics. The S. enterica subspecies IIIa, IIIb, IV and VI strains (with 1 exception) formed significantly (p<0.05) more biofilm in the assay used than S. enterica subspecies I strains (with 2 exceptions). An association (both positive and negative) between the carriage of particular virulence genes and/or resistance to particular antibiotics with the extent of biofilm formation within subspecies was apparent. We further investigated the link between antibiotic resistance and biofilm formation by transforming two strains of each subspecies (one relatively stronger and one relatively weaker biofilm former) with plasmids carrying ampicillin resistance, kanamycin resistance or both ampicillin and kanamycin resistance. The introduction of antibiotic resistance changed biofilm formation in most strains, either positively or negatively, and in both a strain and antibiotic specific manner. This work suggests that antibiotic resistance can significantly influence biofilm formation by Salmonella enterica. This finding has implications for the persistence and spread of this pathogen in food related environments and may result in the emergence of new strains of greater public health concern.