Platelets are tiny cells in your blood that form clots and stop bleeding. Like blood, there is a constant need for platelet donations. Currently, platelet storage is limited only to five days by Food and Drug Administration (FDA() regulations. The study aims to produce a platelet addtive solution using the anti-oxidative property of green tea leaves extract. The study utilized a Mictrowave-assisted extraction of anti-oxidative property of green tea leaves. Other test was performed,l such as Rees-Ecker method, gram staining, peripheral blood smear and pH reagent strip, to examine the effect of green tea leaves extract in maintaning platelet viablility, in vitro. According to evaluation and grading of professional Medical Technologist , there is a significant effect of green tea extract as platelet additive solution to preserve platelet concentrate but not for a longer period of time, specifically seven days of range.