BACKGROUND:: It has always been the highlights to find how to accomplish safe, effective and extensive transfection of the myocardium. OBJECTIVE:: To explore a new feasible method for improving transfection efficiency of non-viral plasmids to the myocardium and for obtaining satisfactory myocardial targeting. METHODS:: We chose PLacZ as a report gene. Wistar rats were randomly divided into five groups: control group, intrapericardial group, intrapericardial negative group, sublingual vein group, sublingual vein negative group. For all the subsets of experiments, hearts were harvested at 6 days after injection. Tissues of heart, lung, liver and kidney were stained with X-gal, and PlacZ gene expression of the heart and other non-targeted organs was observed to decide the gene transfection status and myocardial targeting. RESULTS AND CONCLUSION:: After 6 days of transfection, only rats in the intrapericardial group were stained blue in parts of the myocardium on the atrial, ventricular and apex level. Other groups were negative for X-gal staining in the myocardium, lung, liver and kidney. The intrapericardial injection of microbubbles and some enzymes, as well as plasmids, with the aid of ultrasound, can improve transfection efficiency of plasmids significantly and the heart targeting is satisfactory.Qi YC, Xie XH, Chen W, Li ZH. Improvement of transfection efficiency with plasmid transfected to the myocardium of rats intrapericardially in vivo. Zhongguo Zuzhi Gongcheng Yanjiu. 2012;16(15): 2785-2788. [http://www.crter.cn http://en.zglckf.com]