The influence of water extracts of Spirulina platensis and Chlorella vulgaris (1%) on sensory, chemical and microbiological changes was investigated in vacuum packaged sardine fillets at 4 +/- 1 degrees C for 15 days. Mineral content and bioactive chemical components of microalgae samples were also detected by ICP-MS and GC-MS, respectively. The results showed that S. platensis and C. vulgaris were rich in mineral. Main components in the extracts of C. vulgaris and S. platensis were 3,5-dichloro-6- nitrocholestane (31.74%) and dioctylamine (67.64%), respectively. The extracts prolonged sensorial shelf life of sardine for 3 days although S. platensis group was more preffered than C. vulgaris. These microalgae extracts delayed lipid oxidation and inhibited bacterial growth apart from Gram-positive lactic acid bacteria in sardine meat. The study result revelaed that both extracts can be used as antioxidant and antimicrobial additives to maintain sensory characteristic of sardine fish.