To compare the efficacy of native carvedilol(Cv) with native atenolol(At), we treated 80 cases of essential hypertension(stage I-II) for 4 weeks, using both open-test and double blind randomized imitative methods. The daily dose of carvedilol was 10 mg to 40 mg, and that of atenolol was 50 mg to 100 mg. Both drugs were given once daily. Out of 30 cases of Cv group, carvedilol showed significant efficiency in 20 cases, and was effective in 6 cases. The total therapeutic efficiency was 86.2% (26/30). In the double blind groups(25 patients in each group), those treated with carvedilol(Group A) had 21 effective cases(84.0%) while those treated with atenolol(Group B) had 18 effective cases(72.0%). A lower incidence of adverse effects was observed in carvedilol group. Dizziness occurred similarly in both drugs, but it lasted only a short time and could be tolerated. The recommended dose of 10-30 mg once daily would be appropriate. After treatment there was a significant reduction in blood pressure in both groups(P < 0.01). It suggests that native carvedilol is a safe and effective anti-hypertensive agent.