Flavonoids have the property to inhibit platelet aggregation. This study investigates Crescentia cujete fruit on its flavonoid content using Shinoda test, which confirms its pink apearance. The fruit extract was obtained by maceration using 95% ethanol and extracted through rotary evaporation. This further determines its platelet aggregation activity using Giemsa microplate assay by addition of 4 μL of 0.25M Calcium chloride as inducer. The aggregation activity involved the platelet suspension, human type B+ placed in a 96-well microplate, Aspirin (14.8 mg/mL) as positive and NSS as negative control. These were incubated for five minutes at 37ºC. The initial dose of plant extract administered in the well was 1.00 mg/kg dose and the highest at 251.10 mg/kg employing 0.60 logarithmic interval. Result revealed higher inhibitory action ranging from 50% to 87% with similar findings from positive control. The inhibitory concentration (IC50) yielded a concentration of 6.75 mg/mL and proved an inhibitory effect on platelet aggregation. A non-violet gel formation indicated 100% inhibition and manifested both for fruit extract and aspirin. Hence, it is potent antiplatelet aggregation activity. Acute oral toxicity test was also employed and categorized as non-toxic based on OECD guidelines-423.