Pharmacokinetics, renal clearance and urinary excretion of fixed dose combination antituberculosis drugs (Rifa-4 Schazoo Pakistan) was investigated following oral administration of a single dose (INH 225mg, RMP 450 mg, PZA 1200 mg and EMB 825 mg) in adult healthy and diseased (Pulmonary TB) human male volunteers. The increased maximum concentrations (C max ) of EMB, PZA, RMP and INH in plasma of patients to healthy volunteers may be due to repeated therapy of drugs in patients each day. The elimination half life of isoniazid was significantly lower in healthy volunteers (3.47 ± 0.5 h) as compared to the TB patients (4.04 ± 0.5 h) while its values for PZA were higher in healthy volunteers (7.4 ± 2.2 h) than TB patients (5.7 ± 1.2 h) significantly, however the half life of ethambutol and rifampicin between two populations did not differ significantly (P≤0.05). The mean ±SD values for the volume of distribution for INH and PZA are higher for healthy volunteers compared to the TB patients in contrast to its values for EMB where these are higher in TB patients; however the Vd values were not significantly different for RMP in healthy volunteers and TB patients. An overall significantly (P<0.05) increasing trend was seen for C max :MIC in our studies in healthy volunteers for all drugs except for rifampicin having higher values in patient volunteers compared to healthy volunteers but these higher levels of RMP in patient volunteers did not reach the level of significance. Endogenous creatinine used as an index of glomerular filtration rate in EMB, RMP, PZA and INH in healthy and patient volunteers. EMB and INH respectively have significantly higher clearance rates in healthy volunteers as compared to the patients while RMP and have statistically non significantly different clearance rates. The cumulative percent dose of RMP nonsignificantly (P<0.05) differ in healthy volunteers and TB patients, whereas INH, PZA and EMB have significantly (P<0.05) higher cumulative %dose in pulmonary TB patients compared to healthy volunteers. The mean total protein level had lowered values in active pulmonary TB patients, compared to healthy controls, while creatinine globulin, bilirubin and blood urea were increased in patients and relatively decreased in healthy controls respectively. It was observed that the total level of the cholesterol was significantly lower in patients (141.1 mg/dL) than in healthy controls (211.3 mg/dL). Fasting glucose levels in our studies did not differ significantly in healthy controls (128.6 mg/dL) and pulmonary tuberculosis patients (126.4 mg/dL). The mean BMI in all patients ranges from 14.76 -22.51 and in the healthy volunteers it ranges from 20-25 kg/m 2 .