Objective To investigate the effect of ω-3 fish oil fat emulsion on monocyte chemoattractant protein-1(MCP-1) and cellular immunity in elderly patients with stroke associated pneumonia(SAP)．Methods Totally 60 elderly patients with SAP were randomly divided into routine treatment group and fish-oil group receiving ω-3 fish oil fat emulsion plus routine treatment. Meanwhile, 30 healthy elderly was selected as normal control. The levels of serum MCP-1 and T-cell subset were assessed before and 8 day after administration．Results The clinical effective rate of fish-oil group was higher than traditional treatment group(P＜0.05). The level of serum MCP-1 in elderly patients with SAP was increased greatly compared with normal control elderly(P＜0.01), while it was reduced after treatment(P＜0.01). The change of serum MCP-1 in fish-oil group was greater than that in routine treatment group (P＜0.01). Compared with the normal control elderly, the ratio of CD4+/CD8+ cells was significantly lower in elderly patients with SAP and was increased after treatment. The ratio of CD4+/CD8+ cells was increased significantly in fish-oil group than that in routine treatment group(P＜0.01). Conclusion ω-3 fish oil fat emulsion may play a protective role on senile patients with SAP by improving function of cellular immunity and reducing the level of serum MCP-1.