Estrogen is believed to have direct protective action on the cardiovascular system. Estrogen action may involve the p38 mitogen activated protein kinase (p38-MAPK). To investigate the role of gender and of p38-MAPK in catecholamin induced hypertrophy, male (8) and female (11) mice received a 7 days course of isoprenaline or only carrier (6 and 9, respectively). Blood pressure, variability of blood pressure and heart rate, baroreflex activity, left ventricular end-diastolic pressure, and indices of myocardial contractility were obtained. Parameters did not differ between groups. Indices of cardiac hypertrophy revealed hypertrophy in treated mice (heart/body weight relation - 4.5 and 4.6 mg/g in control males and females, and 5.1 and 5.0, respectively in treated mice), but without differences between male and female. p38-MAPK was not elevated in treated animals compared with untreated. Our results show that isoprenaline is effective in causing hypertrophy in mice. There is no influence from gender on p38-MAPK activity, anatomical or hemodynamic parameters.