Effects of epibrassinolide (EBR), one of the brassinosteroids (BRs), on culture of Chinese cabbage mesophyll protoplasts were researched. The addition of EBR to the liquid culture medium increased the cell division rate and the amount of soluble protein of the protoplasts during culture. These results showed that EBR enhanced cell reproduction of Chinese cabbage mesophyll protoplasts. EBR 10^-1 mg/L was especially effective. After 3 weeks of culture, there were more cell clusters in the petri dishes containing EBR than in those not containing EBR. The number of clusters increased in direct proportion to the EBR concentration. The clusters in liquid medium were transferred to agarose solidified medium which contained the same concentration of EBR as liquid culture, and after that colony formation was observed. As the result, the addition of 10^-1 mg/L EBR obviously enhanced colony formation of the protoplasts. It was shown that EBR was effective in multiplication of the protoplasts.