Microbial secondary metabolites are useful high value products that are normally produced by liquid culture; but could be advantageously produced by solid-state fermentation (SSF). Particularly if SSF could benefit from a deeper understanding of microbial physiology in a solid environment. Recent research indicates that different kind of secondary metabolites can be produced by SSF: antibiotics, phytohormones, food grade pigments, alkaloids, etc. Physiology in SSF shows several similarities with physiology in liquid medium, so similar strategies must be adapted for efficient processes. However, there are certain particularities of idiophase in solid medium which dictate the need for special strains.