The purpose of this study is to investigate the correlation between users' preferences of personality types and their attitude towards patterns of Web OPAC use mainly focus on their search behaviour and their preferences for the interface. Data was collected through the MBTI test and self-designed online questionnaire. The original MBTI personality types were re-coded into 4 categories of preferences of personality types, that is, E(Extraversion)- I(Introversion), S(Sensing)-N(iNtuition), T(Thinking)-F(Feeling), and J(Judging)-P(Perception) and then analysed their correlation with patterns of Web OPAC use by Pearson's correlation coefficient (r) in SPSS Windows Ver. 11.0. It is noteworthy that 9 out of 28 factors of Web OPAC search behaviour and preferences for interfaces show statistically significant correlations with users' MBTI preferences of personality types.