This study was undertaken to investigate the influence of cultural conditions on the production of antibacterial red pigment by Serratia marcescens IBRL USM 84. This isolate exhibited maximal antibacterial red pigment production of 37.17 U/ml which was achieved at 40 hours of cultivation time when cultivated in  marine broth with improved  conditions, including the addition of 0.2%  (w/v) of agar, cultivation temperature at 25°C, initial medium pH of 7, agitated at 150 rpm and 2% inoculum size (1×10⁹ cells/ml). There was an increment of 164% of red pigment production after improvement compared to before improvement of cultural conditions. The results suggested different cultural conditions have a significant impact on the secondary metabolite production by the bacterium to gain a high yield.