Streptomyces is a genus of Gram-positive, aerobic, filamentous and non-acid-fast actinobacteria that belongs to the family streptomycetaceae and represents the largest genus of actinobacteria. It is common in various environments; soil, composts, water (rivers and marine) and plants. The genus comprises more than 600 species with validated names. The most interesting features of Streptomyces is its ability to produce bioactive secondary metabolites, such as antifungal, antibacterial, antiviral, antitumor, anti-hypertensives, immunosuppressant, and several others. The genus produces over two-thirds of the clinically useful antibiotics of natural origin related to aminoglycosides, β-lactams, macrolides and tetracyclines. The production of most antibiotics is species specific, and the species produce them to compete with other microorganisms in the same habitats. In addition, these antibiotics protect the plant against microbial pathogens. The objectives of the current review are to shed light on the genus Streptomyces; diversity, general features and the role of this genus in production of highly valuable antimicrobial agents that commonly used in treatment of some virulent pathogens.