Background: There are some experimental evidences in vitro suggesting involvement of p53 in the mechanisms of left ventricular hypertrophy (LVH). The aim of this study was to investigate in vivo the expression of protein p53 during the development of LVH in rats. Methods: We monitored the expression of p53 protein in the nucleus and cytozol left ventricular homogenates from adult rats with induced LVH by abdominal aortic banding (AAB) and sham operated at days 10, 15, 20, 25, 35 and 45 post-operation using Western blot analysis. Results:The expression of p53 in the nucleus on the 15th and 25th day was significantly lower than on the other days in the AAB rats and coincides with marked increase in echo-left ventricular mass (LVM) and actual heart weight (HW) in AAB rats. Relative to SH, p53 protein expression in the nucleus in AAB rats increased significantly by 73% (P<0.001) at day 20th and was attended with significant reduction of the HW in the group with AAB. Furthermore, the level of p53 protein in the nucleus correlated well with echo-left ventricular mass and actual heart weight in AAB groups (R= -51 and R= -50, respectively, both P<0.0005, n=54). Conclusions: In our model following the development of LVH during a relatively long period of time and providing the changes in short intervals, it was found that the progression of LVH is not a linear process but a phase one and is accompanied with an active alteration in the expression of p53.