This study included determining the activity of crude secondary etabolites produced by Streptomyces and their effect on the growth cancer cells in vitro. Twenty samples of soil were collected from different places of Baghdad, and five isolates referred as Streptomyces, were cultivated using Gauza agar medium. The isolates went through microscopical and cultural examinations as well as biochemical tests, growing at different salt concentrations on SY- media, and growing at different incubation temperatures. Results showed that none of the isolates were not tolerant to neither high nor low temperature (28- 50ºC), also it was noticed that these isolates grow better when pH value range between 7- 8. The ability to produce antibacterial substances was studied by determining the biological activity against gram +ve and gram –ve bacteria and eukaryotes, the results showed that two of the five isolates had the ability to inhibit the growth of these microorganisms because of their ability to produce antibiotic- like substances, they were called ERM1 and ERM2. These results were also strengthened by thin layer paper chromatography, and it was found that these two isolates were able to produce Neomycin, Streptomycin, Doxorubicin, Bleomycin and Tetracycline. When the factors affecting the productivity of these isolates were determined, it was found the growth at 28°C and pH 7.0 for five days was the best to produce antibiotics. Cytotoxic activity was tested for every crude extract of ERM1 and ERM2 (10, 20, 30, 40, 50 and 60) μg/ml on the cancer line (Hep-2) for 28 hrs, the result indicated that the crude extract showed inhibitory activity on the growth of cancer cells.
