Objectives To examine the synergistic antibacterial activity of violacein and silver nanoparticles (AgNPs) against ATCC bacteria, Staphylococcus aureus, Escherichia coli and two bacteria isolated from bovine mastitis. Methods Violacein from Chromobacterium violaceum and biogenic AgNPs from Fusarium oxysporum were evaluated in antimicrobial tests. Results E. coli isolates were not inhibited by violacein at concentrations up to 400 mu M and they showed sensitivity for AgNPs between 62.5 and 250 mu M. Staphylococcus aureus showed sensitivity to violacein with MIC of 200 mu M, and the MIC with AgNPs between 250 mu M and 125 mu M. It was also tested the association between the two compounds through a concentration gradient and was observed the reduction of the MIC in the combination for both strains. Conclusion The bactericidal effect of violacein against S. aureus was better when combined with AgNPs (synergistic).