The pathogenesis of drug-induced hepatotoxicity (DIH) is still not entirely clear for most anti TB drugs including rifampicin. Hypersensitivity is a definite possibility Rifampicin induced hepatitis has been postulated to occur as a part of systemic allergic reaction and, due to unconjugated hyperbilirubinaemia as a result of competition with bilirubin for uptake at hepatocyte plasma membrane. DIH caused by rifampicin occurs earlier as compared to isoniazid. While a dose related toxicity may exist, a direct correlation between serum drug levels and hepatotoxicity has not been well reported. Thus the clinical relevance of therapeutic monitoring of serum rifampicin concentrations in managing DIH is still being explored.