Diastolic dysfunction represents an important pathophysiological intermediate between hypertension and heart failure. In the last two decades, the prevalence of heart failure patients having normal or near normal ejection fraction (EF) has increased to around 60 %. It thus poses a great morbidity and mortality risk to the population. In view of present scenario of high prevalence, lack of evidence-based therapy, and limited clinical trials, this study aimed to evaluate how a Unani formulation affects the improvement of the left ventricular diastolic function. This clinical trial was set up as a randomized, placebo-controlled study involving 35 participants, with 18 individuals in the test group and 17 in the control group. Test group received 3.5 g of a polyherbal Unani formulation in capsule form along with 35 mL of an extract of Borago officinalis L. (Arq-e-Gaozaban), divided into two doses after meals. Meanwhile, the control group received a placebo in the same manner over an eight-week period. Follow-ups were conducted every 15days to assess both subjective and objective parameters in all participants. The test formulation shows significant improvement in dyspnea and diastolic function from baseline to the end of trial (p<0.05), slight improvement in palpitations (p>0.05) and highly significant improvement in easy fatigability (p=0.001) as compared to the control. The present study shows the effectiveness of the test drug in enhancing the diastolic function of left ventricle and alleviating other symptoms associated with ventricular diastolic dysfunction. Nevertheless, additional research with longer follow-up durations is necessary to clarify its efficacy and establish optimal treatment approaches for ventricular diastolic dysfunction in Unani medicine.