Solid-state fermentation (ssf) is defined as the growth of microbes without free flowing aqueous phase. The ssf is alternative to submerged fermentation for production of value added products like antibiotics, single cell protein, PUFA’s, enzymes, organic acids, biopesticides, biofuel and aroma production. However, the advantages of ssf in various processes are found to be greater than in submerged fermentation. This paper reviews the advantages of solid-state fermentation over submerged in production of different value added products, important features of various bioreactor designs, recent developments in utilization of various agro-industrial residues as substrates and the importance of mathematical modeling. With advances through modeling and optimization techniques, production-using ssf is advantageous and appropriate for production of many value added products like enzymes, antibiotics, and organic acids. This technique not only decreases the cost of the process but also makes product cheaper for consumers.