A simple, sensitive and precise RP-HPLC-DAD method was developed and validated for the determination of olmesartan medoxomil (AT-II receptor blocker) in the presence of its degradation products. Olmesartan medoxomil and all the degradation products were resolved on a C18 column with the mobile phase composed of methanol, acetonitrile and water (60:15:25, V/V/V, pH 3.5 by orthophosphoric acid) at 260 nm using a photodiode array detector. The method was linear over the concentration range of 1-18 μg mL-1 and precise with RSD < 1 % in intra- and inter-day study. Excellent recoveries of 99.3 ± 0.9 to 100.8 ± 1.2% proved the accuracy of the method. Developed method was specific, as indicated by chromatographic resolution > 2.0 for each peak and sensitive with LOD 0.03 μg mL-1 and LOQ 0.1 μg mL-1. The method was used to study the drug degradation behavior under forced conditions. Four degradation products (DP-I, II, III, IV) were formed during the degradation study in 0.1 mol L-1 HCl whereas only DP-I, II and III were formed in water, 0.01 mol L-1 NaOH and 3% H2O2. No significant thermal or photolytic degradation was observed in solid drug. The method was applied successfully for the assay of olmesartan medoxomil in the tablet dosage form. U ovom radu razvijena je i validirana jednostavna, osjetljiva i precizna RP-HPLC-DAD metoda za odredivanje olmesartan medoksomila (inhibitor AT-II receptora) u prisutnosti njegovih razgradnih produkata. Olmesartan medoksomil i razgradni produkti kromatografirani su na C18 koloni uz mobilnu fazu metanol/ acetonitril/voda (60:15:25 V/V/V; pH 3,5 podešen ortofosfornom kiselinom) pri 260 nm uz detektor s fotodiodnim nizom. Metoda je linearna u koncentracijskom rasponu 1-18 μg mL-1 i precizna s RSD < 1% tijekom ispitivanja repetabilnosti i intermedijarne ponovljivosti. Povrat od 99,3 ± 0,9 do 100,8 ± 1,2% dokazuje točnost metode. Razvijena metoda je specifična na što ukazuje kromatografsku rezoluciju veću od 2,0 i osjetljiva (LOD = 0,03 μg mL-1 i LOQ = 0,1 μg mL-1). Metoda je upotrebljena za praćenje razgradnje olmesartan medoksomila u uvjetima potencirane razgradnje. U 0,1 mol L-1 HCl detektirana su četiri razgradna produkta (DP-I, II, III, IV), a u vodi, 0,01 mol L-1 NaOH i 3% H2O2 samo DP-I, II i III. U čvrstom agregatnom stanju nije primječena značajna termička ni fotolitička razgradnja ljekovite tvari. Metoda je uspješno primijenjena za odredivanje olmesartan medoksomila u tabletama.