Imidazo[4,5-b]pyridines are amongst the oldest known heteroaromatic derivatives. Their structural similarity with purine basis has however aroused the curiosity of biologists and resulted in the developments of innovative bioactive compounds. This review thus firstly describes the main synthetic ways currently used to produce imidazo[4,5-b]pyridine derivatives, and secondly gives examples of their potential, especially focusing on protein inhibition abilities, thus opening the way to applications as anti-- cancer or antimicrobial agents.