Mulberry are mainly used as food for the silkworms and they are eaten as vegetable or used as cattle fodder in different parts of the world. Mulberry fruit is well known as a good source of anthocyanins with many biological activities. Mulberry (Morus nigra) is a fruit not known only for its nutritional qualities and its flavour, but also for its traditional use in natural medicine as it has a high content of active therapeutic compounds. In this study, the effect of the Morus nigra L., black mulberry fruit extract supplement on the biology of mulberry silkworm was investigated. Fruits were extracted by cold-water method. The mulberry leaves were dipped in the fruit extract. The treated leaves were offered to the last larval instar of silkworm at concentrations of 25, 50 and 100%. The results indicated that mulberry fruit extract enhanced the biology of silkworm and silk production. The concentration of 50% of fruit extract gave the best results. Which improve the mean weight of mature larvae by 23%, fresh cocoon by 38.2%, pupae by 40.9% and cocoon shell by 20.9% over the control.