This paper describes the characteristics and levels of harmonis on PT,PLN's 20 kV medium voltage and low voltages distribution network in west java and banten. In this papaer a study and measurements of harmonics for vaious types of load in some types of industries are conducted and verified. This paper also discuss the phenomenon of harmonics, the effect on the distribution system, harmonic-producing sources, standars and recommended practice limits for medium voltage and low voltage networkk according to the IEEE 519and IEC 61000 harmoniic standard. Harmonic measurement methods were done on two types by measuring the customer's 20 kV medium voltage and low voltage distribution subtation network. The first method was done by measuring with continous longging for a week duration on 8 samples of medium voltage customer to know the harmonics levels and their probability occurrence. The second method was done by instantaneous measurement for 5 minutes durng peak load on 20 samples of low voltage distribution loads. From the measurement result shows that harmonic current conditions THDi on the measured distribution subtation are all above 5 %,and 70 % of customers who have THDi measured more than 10%. Other issues on the load harmonic curents that cause pallution to the harmonic current grid are also verified. The measurement of neutral current due to the harmonic currents in low voltage side of distribution transformer neutral circuit provides that 17 out of 20 smples measured were have larger value taht the calculated condition without harmoniecs pollution. Keywords: Harmonic characteristic, medium and low voltage network, total harmonic distortion, nautral current.