Pathological cardiac hypertrophy is characterized by deleterious changes developed in cardiovascular diseases, whereas microRNAs (miRNAs) are involved in the mediation of cardiac hypertrophy. To investigate the role of microRNA-26a (miR-26a) in regulating cardiac hypertrophy and its functioning mechanisms, overexpression and suppression of miRâ26a via its mimic and inhibitor in a transverse abdominal aortic constriction (TAAC)-induced rat model and in angiotensin II (Ang II)-induced cardiomyocytes (CMs) was performed. In the rat model, the heart weight (HW) compared with the body weight (BW), the CM area, and expression of the hypertrophyâassociated factors, atrial natriuretic factor (ANF) and βâmyosin heavy chain (βâMHC), were assessed. In CMs, the protein synthesis rate was determined using a leucine incorporation assay. Mutation of the GATAâbinding protein 4 (GATA4) 3'âuntranslated region (UTR) and overexpression of GATA4 were performed to confirm whether GATA4 is the target of miRâ26a. The results indicated that miR-26a was significantly downregulated in the heart tissue of the rat model, as well as in Ang IIâinduced CMs (P<0.05). The TAAC-induced rat model exhibited a higher HW/BW ratio, a larger CM area, and higher expression levels of ANF and βâMHC. CMs, upon Ang II treatment, also demonstrated a larger CM area, higher levels of ANF and βâMHC, as well as accelerated protein synthesis. miRâ26a was not able to regulate GATA4 with mutations in the 3'âUTR, indicating that GATA4 was the direct target of miRâ26a. Overexpression of GATA4 abrogated the inhibitory functions of miRâ26a in cardiac hypertrophy. Taken together, the present study suggested an antiâhypertrophic role of miRâ26a in cardiac hypertrophy, possibly via inhibition of GATA4. These findings may be useful in terms of facilitating cardiac treatment, with potential therapeutic targets and strategies.