OBJECTIVE:To study the in vitro dissolution of Enalapril maleate and folic acid tablet. METHODS:HPLC was performed on the column of Agilent HC-C18 with mobile phase A of acetonitrle-phosphate buffer solution(70:30,V/V) and mobile phase B of acetonitrle-phosphate buffer solution(5:95,V/V)(gradient elution) at a flow rate of 1.0 ml/min,detection wavelength was 215 nm,column temperature was 50 ℃,and volume injection was 80 μl. Media were water,hydrochloric acid solution(pH 1.2),phosphate buffer solution(pH 5.0)and phosphate buffer solution(pH 6.8),medium volume was 900 ml and rotation speed was 50 r/min. The dissolution behavior of enalapril maleate in Enalapril maleate and folic acid tablet in 4 media were studied and compared with the dissolution behavior in vitro in original preparation of Enalapril maleate tablet,meanwhile,the dissolution behar-ior of folic acid in Enalapril maleate and folic acid tablet in phosphate buffer solution(pH 5.0)were studied and compared with dis-solution data of folic acid preparation in Japanese Orange Book to evaluate the intrinsic quality. RESULTS:The linear range was 0.561-14.03μg/ml for enalapril maleate(r=0.999 9)and 0.043-1.085μg/ml for folic acid(r=0.999 9),respectively;RSDs of pre-cision and stability tests were lower than 2.0%;recoveries of enalapril maleate in 4 media were 100.63%-102.33%(RSD=0.72%, n=9),99.27%-100.44%(RSD=0.41%,n=9),99.71%-100.29%(RSD=0.15%,n=9)and 96.74%-99.19%(RSD=0.79%,n=9),respectively. Recoveries of folic acid were 100.18%-101.63%(RSD=0.48%,n=9),97.73%-101.81%(RSD=1.32%,n=9),99.60%-102.24%(RSD=0.74%,n=9)and 100.00%-102.76%(RSD=0.90%,n=9),respectively. In 15 min,the dissolution of enalapril maleate of 2 preparations in 4 dissolution media were more than 85%;dissolution speed of folic acid in Enalapril male-ate and folic acid tablet was faster than that in folic acid preparation in phosphate buffer solution(pH 5.0). CONCLUSIONS:The method is suitable to determine the dissolution of Enalapril maleate and folic acid tablet;the in vitro dissolution curve of enalapril maleate in Enalapril maleate and folic acid tablet is similar to Renitec,and the in vitro dissolution of folic acid is better than folic acid preparation.