To investigate the antimicrobial activity of secondary metabolites from Serratia marcescans S823. The strain Serratia marcescans S823 was screened for its antibacterial activity. The active components from the bacterium were isolated by bioactivity-guided analysis. Their structures were identified by chemical and spectroscopic methods to be prodigiosine (PG) (1), serratamolide A (2) and serratamolide G (3), which is a new compound. The MIC and MBC of prodigiosine and serratamolide G were 6.25 μg.mL-1 and 12.5 μg.mL-1 against C. albicans and 6.25 μg.mL-1 and 25 μg.mL-1 against B. thuringiensis respectively. They might be potential alternative treatment options for Candida albicans infection. This study encourages further investigation of natural products as new antibiotics.