Abstract: Objective To identify the effects of storage time on platelet function tested with PL-11 analyzer under room temperature. Methods Citrated antecubital vein blood samples of graduate students in grade 2012 of Chinese PLA Medical School (n=20) and coronary heart disease (CHD) outpatients (n=20) treated with dual-antiplatelet drugs in the department of cardiology were drawn and tested by PL-11 analyzer at 3 testing points:2, 4 and 8 hours after blooding. The maximum platelet aggregation ratio was tested with 3 different activators:arachidonic acid (AA), adenosine di-phosphate (ADP) and collagen. Results Healthy young men:AA-induced platelet aggregation ratio showed no difference between 2 h, 4 h and 8 h (P> 0.05). When ADP used as the activator, platelet aggregation ratio reduced apparently at 4 h compared with 2 h (P< 0.01), and it reduced to 4.3% at 8 h (P< 0.01). There was a clear reduction of collagen-induced platelet aggregation at 4 h compared with 2 h (P< 0.01), while no difference was found between 4 h and 8 h (P> 0.05). Patients treated with dual-antiplatelet drugs:AA-induced results showed no statistic difference between 2 h, 4 h and 8 h (P> 0.05). ADP-induced results showed an obvious reduction at 4 h, while no difference was found between 4 h and 8 h (P> 0.05). Collagen-induced aggregation ratio reduced apparently at 8 h after blood sampling (P< 0.01). Conclusion Storage time affects the results of PL-11 platelet function test with limited influence on AA-induced platelet aggregation ratio, whatever in healthy men or patients treated with dual-antiplatelet drugs. ADP- or collagen-induced platelet aggregation ratio reduces as the time delay extending. The time delay between collection, transport and analysis should ideally be preferable in 4 hours when AA used as activator or 2 hours when ADP and collagen used as activators.