Pulmonary arterial hypertension (PAH) is a pulmonary vascular disease causing right ventricular (RV) hypertrophy, failure, and death. Some miRNAs are involved in the pathophysiology of PAH. As the current treatments cannot prevent the progression of the disease, we investigated whether 3 plant derivatives, namely perillyl alcohol (PA), quercetin (QS), and berberine (BBR), can improve RV function and affect the expression of miR-204, miR-27a, and biochemical factors in monocrotaline-induced PAH (MCT-PAH). Thirty-six rats were divided into control (CTL), MCT, MCT+Veh (vehicle), MCT+PA, MCT+QS, and MCT + BBR groups (n = 6 each). After inducing PAH using MCT (60 mg/kg), PA (50 mg/kg), QS (30 mg/kg), and BBR (30 mg/kg) were administrated daily for 3 weeks. miR-204 expression, total antioxidant capacity, and antiapoptotic protein Bcl-2 significantly declined in the RV of PAH rats, and PA, QS, and BBR treatment significantly compensated for these decreases. Proapoptotic protein Bax and p21 cell cycle inhibitor increased in the RV. All 3 herbal derivatives compensated for Bax increase, and BBR caused a decrease in p21. TNFα, IL-6, and malondialdehyde increased in the RV, and PA, QS, and BBR significantly counterbalanced these increases. miR-27a expression was not affected by MCT and plant derivatives. Overall, PA, QS, and BBR improved ventricular disorders in rats with PAH by decreasing inflammation, apoptosis, and fibrosis and increasing the antioxidant-to-oxidant ratio. Therefore, these herbal derivatives may be considered as target therapeutic goals for this disease either alone or in combination with current medications.