Abstract: In order to elucidate the effects of fish oil on the growth and metabolism of prostate cells, in the present paper an epithelial cell (RWPE-1) and prostate cancer cell (PC-3) were employed. Effects of fish oil on cell growth and apoptosis were investigated by MTT assay and flow cytometry after treatment with fish oil.Also gas chromatography was used to analyse fatty acids composition and inflammatory factors (TNF-α, IL-6, LXA4 secreted by cells were detected using ELISA. Results showed that condensed fish oil used in our study had little damage to RWPE-1 cell growth, but the viability of PC-3 cells reduces to 70.34% and the apoptosis rate of PC-3 cells is up to 15.47%±0.64% after treated with fish oil for 48 h which was diluted into 50 times. The proportions of GLA, AA, EPA and DHA in PC-3 cells increased markedly, which had no significant increase in RWPE-1 cells. For RWPE-1 cells, the secreted LXA4 maintains almost in a same level and the expression of IL-6 and TNF-α rises gradually. However, PC-3 cells resulted in higher levels of LXA4 and lower expressions of IL-6 and TNF-α when incubated with fish oil. Effects of condensed fish oil used in our study on the growth of these two kinds of prostate cells are quite different.