10.22376/ijpbs.2019.10.1.p1-12 Volume 1 Issue 4 2010 (October - December) lessThan i greaterThan Micrococcus luteus lessThan /i greaterThan was employed for the assay of rifampicin in fixed-dose combinations (FDCs) of anti-tubercular drugs containing rifampicin, isoniazid, pyrazinamide and ethambutal. The microbiological assay was compared with spectrophotometric assay for estimation of rifampicin in the FDCs as well as in dissolution studies of the FDCs. The microbiological method was found to be more sensitive and accurate as compared to spectrophotometric assay and did not show any interference in the presence of other anti-tubercular drugs. The limits of detection and quantification for microbiological method were 0.1 µg/ml and 0.64 µg/ml, respectively. Sarbjit Singh Jhamb, Raman Preet Singh Rifampicin, Micrococcus luteus, microbiological assay, pharmaceutical formulations, fixed dose combination 294-302