Isoniazid, otherwise known as isonicotinyl hydrazide, is an antibiotic used for the treatment of latent and active tuberculosis infections. It is one of the oldest drugs for the treatment of TB. The chemistry of isoniazid and its derivatives are truly exciting owing to their plethora of applications in diverse and promising areas, which is undoubtably beneficial to the humankind. Most importantly, the therapeutic uses of these compounds e.g microbicidal, antioxidant, anticancer and DNA binding applications are cardinal in human healthcare system. Furthermore, the combined effect of isoniazid with rifampicin, ketoprofen, etc. is also reported.