Abstract Relationship between big five personality traits and online purchase intension was determined by this study. Researchers stated their hypothesis as follows : Big five personality could predict the intention of online purchase from the students who majoring in Psychology at Universitas Prima Indonesia Medan. There were 186 Psychology's students participating in this study and they was selected using purposive sampling technique. Assumption testing has been done by requirements test analysis including normality test, test of heteroscedasticity, also multicollinearity test. Data was analyzed using multiple regression analysis method through SPSS 16 version. Results of data analysis indicate the relationship between the Big Five Personality Trait and Online PurchaseIntention with the provement of the F value = 5,864 and the significancy value (p) = 0.000; (p<0.05). Results of this study showed that one of the five Big Five Personality dimension having correlation to Online Purchase Intention. It is the dimension of Openness to New Experience with significance (p) = 0.003; (p<0.05).   Abstrak Penelitian digelar untuk mengkaji hubungan antara tipe kepribadian Big Five terhadap intensi membeli online. Tipe kepribadian Big Five dapat menjadi prediktor dalam mengukur intensi membeli online pada mahasiswa/i Fakultas Psikologi Universitas Prima Indonesia Medan merupakan hipotesa yang diajukan pihak peneliti. Subjek penelitian ini berjumlah186 mahasiswa fakultas Psikologi dan dipilih menggunakan metode purposive sampling. Uji asumsi dilakukan melalui uji prasyarat analisis yaitu uji auto korelasi, uji multikolinearitas, uji normalitas, uji heteroskedastisitas. Analisa regresi berganda dalam penelitian ini digunakan sebagai analisis data dengan bantuan program SPSS versi 16. Analisa data ini membuktikan bahwa adanya hubungan tipe kepribadian big five dan intensi pembelian online dengan nilai F = 5,864 dan nilai sig. (p) = 0.000; (p<0,05). Hasil lainnya pada penelitian ini juga menunjukkan bahwa salah satu dimensi memiliki hubungan dengan intensi membeli online yaitu openness to experience dengan (p) = 0,003; (p<0,05)