Introduction: studies on Maytenus trees comprising forsskaoliana, krukovii, and ilicifolia species showed depressing effects on the blood pressure and the heart rate. Objectives: to experimentally analyze the effects of Maytenus macrocarpa leaves on the heart rate, the electrocardiographic patterns, the respiratory rate, and the temperature. Method: this study was exploratory, analytical, and experimental. Albino rats were grouped in 9 groups of 8 rats each. Group 1 (control: Halatal), group 2 (placebo: distillated water), group 3 (adrenaline), group 4 (atropine), group 5 (acetylcholine), group 6 (propranolol), group 7 (500 mg/kg chuchuhuasi), group 8 (1 000 mg/kg chuchuhuasi), and group 9 (1 500 mg/kg chuchuhuasi). The rectal temperature was measured with a mercury thermometer, whereas the direct count allowed measuring the respiratory frequency. The polygraph registered electrocardiogram and heart rate as well. The MATLAB program analyzed data from the electrocardiogram. The statistic validation was performed with ANOVA, Tuckey, Wilcoxon, and Shapiro-Wilk tests. Results: Maytenus macrocarpa showed depressing effects on the cardiac frequency, being more effective at 1 500 mg/kg doses (average 308.6 ppm), higher negative inotropic effect at 1 500 mg/kg doses (average P wave 0.08300 mv, average R wave 0.1539 mV). Severe bradypnea was shown at 1 500 mg/kg doses (average RF 51.6 rpm), as well as hypothermia (average T° 31.84 °C). Conclusion: Maytenus macrocarpa demonstrated bradycardic as well as depressing effects on respiratory frequency and body temperature.