Sustained release nanoformulations of second line anti-tubercular drugs can help in reducing their dosing frequency and improve patient's compliance in multi-drug resistant tuberculosis (MDR TB). The objective of the current study was to investigate the pharmacokinetics and tissues distribution of ethionamide encapsulated in poly (DL-lactide-co-glycolide) (PLGA) nanoparticles. The drug loaded nanoparticles were 286 ± 26 nm in size with narrow size distribution, and zeta-potential was -13 ± 2.5 mV. The drug encapsulation efficiency and loading capacity were 35.2 ± 3.1%w/w and 38.6 ± 2.3%w/w, respectively. Ethionamide-loaded nanoparticles were administered orally to mice at two different doses and the control group received free (unencapsulated) ethionamide. Ethionamide-loaded PLGA nanoparticles produced sustained release of ethionamide for 6 days in plasma against 6 h for free ethionamide. The Ethionamide was detected in organs (lung, liver, and spleen) for up to 5-7 days in the case of encapsulated ethionamide, whereas free ethionamide was cleared within 12 h. Ethionamide-loaded PLGA nanoparticles exhibited significant improvement in pharmacokinetic parameters, i.e. C(max), t(max), AUC₀₋∞, AUMC₀₋∞, and MRT of encapsulated ethionamide as compared with free ethionamide. Drug in nanoparticles also exhibited a dose proportional increase in the AUC₀₋∞ values. The pharmacodynamic parameters such as AUC₀₋₂₄/MIC, C(max)/MIC, and Time > MIC were also improved. PLGA nanoparticles of ethionamide have great potential in reducing dosing frequency of ethionamide in treatment of MDR TB.