Mycelia products from wild-form Cordyceps sinensis could be constantly produced in a large scale and would be a better source of this herbal medicine. Our purpose was to investigate the immunological effects of an orally administered hot-water extract cultured mycelium of C. sinensis in lupus-prone (NZB/NZW) F1 hybrids. Forty female mice were divided into four groups and were given 2.4 mg/g/day oral doses of C. sinensis starting at three (group A), six (group B), or eight (group C) months of age, whereas the remaining group (group D) served as a control. Survival, proteinuria, and titers of anti-double-stranded DNA autoantibodies were evaluated. Treatment with C. sinensis resulted in increased survival, decreased proteinuria, and reduced titers of anti-double-stranded DNA antibody in groups A and B. Moreover, the mice in groups A and B showed significantly reduced percentages of CD4(+) T cells (*P < 0.05) and increased percentages of CD8(+) T cells in peripheral blood mononuclear cells (PBMC) after C. sinensis administration. At 6 months of age, the proliferation rate of BrdU-incorporated spleen cells was significantly decreased after 48 and 72 h of C. sinensis treatment (**P < 0.01) in group A of mice. In conclusions, early medication with C. sinensis induced the redistribution of PBMC and attenuated the disease severity of lupus in (NZB/NZW) F1 mice.