This article aims to illustrate the outlier analyses applied to bibliometrics analysis. Outlier is an observation that is unusually large or small relative to the data set. There are three possible causes to outlier: incorrect value; the outlier comes from another population, or that the measurement is correct, but represents a rare event. So, outlier can potentially have a deeper impact on the bibliometric study. It is important to identify outlier to at least to perform alternative analysis with or without the outlier.