The immunomodulating effect of Salicornia herbacea polysaccharides on BALB/c mice splenocytes was investigated. Crude (CS) and fine polysaccharide (PS) extracts with potential biological activity were prepared from S. herbacea. For in vitro experiments, splenocytes and separated T cells were treated with CS and PS (0.5, 1, 2, and 4 mg/mL). For in vivo experiments, the CS and PS were orally administered to BALB/c mice every day for 2 weeks. For basic data analysis, physiological parameters were recorded. Cell proliferation of splenocytes and T cells was used as an index for immunomodulating activity. The proliferation of splenocytes and separated T cells was 3.2 and 3.5 times higher than the control, respectively. Moreover, when splenocytes were treated with mitogen, the highest proliferation rate was observed in splenocytes cultured with PS. Interestingly, the stimulative activity of PS was more strongly exerted through $CD4^+$ T cells than through $CD8^+$ T cells.