This paper describes synthetic modifications of the C-19 position of tuberactinomycin B (viomycin) and related analogs. The in vitro antibacterial activity of selected analogs against Pasteurella multocida, Escherichia coii and methicillin-resistant Staphylococcus aureus is also discussed. Although C-19 arylation and thiolation did not improve antibacterial activity, C-19 benzyl carbamates, benzyl- and phenyl ureas were found to be more potent than the parent antibiotic.