Abstract Cyclic adenosine 3′,5′-monophosphate (cyclic AMP) is present in saprophytic fast growing as well as pathogenic and non-pathogenic slow growing mycobacteria. Apparently there does not seem to be any direct relationship between either intra- or extra-cellular cyclic AMP content with the growth rate of the bacteria. Intracellular cyclic AMP content is much higher than that of E . coli grown on a similar carbon source. Glucose when added to the cells suspended in phosphate buffer lowers the intracellular cyclic AMP content by 6–8 fold.