The purpose of this quasi-experimental is to assess the effectiveness of participation in self-help group on self-care in patients with essential hypertension. The total of 60 essential hypertension patients who were first diagnosed at Chiangraiphachanukruk Hospital during November 1993 to February 1994 were included into the study. They were devided equally into two groups and randomly assigned to the self-help group on self-care and control group. The self-help group was classified into 3 groups, 10 each, inorder to participation in a 1 1/2 hours session of intervention once a week during the 6 weeks of study. The regular advice program from the Department of Out-Patient was given to the control group once amonth according to the follow-up visit. The intervention on self-care behavior was collected by using the structure questionnaire which constructed by researcher. The weight, height and diastolic blood pressure were measured both before and after starting the intervention. It was found that the patients who participated in self-help group had gained a significantly better self-care than the regular advice control group (p<.001). The result was also shown that the weight lost in the self-help group was significantly better than the regular advice group (p=.022). It was, however the decreasing of diastolic blood pressure in the self-help group was not statistically different from the control group (p=.134). It could be encluded that for patients with essential hypertension in self-help group program was more effective than the regular advice program. It is, therefore, the participation in self-help group with the emphasis on sharing and learning from the experiences of others in a group for solving-problem increased the motivation for efficiency self-care behavior modification. Due to the short period of study, the effect on lower diastolic blood pressure cannot be detected. However the self-help group program for a longer period of study is recommended.