The present longitudinal study examined the changes in foreign language reading anxiety and its predicting effects on Chinese university students' reading English performance. The 29-item Foreign Language Reading Anxiety Scale (FLRAS), a background questionnaire and a reading quiz were administered to two intact classes of an English Reading course at three time points of an 18-week semester at a university in Beijing. The major findings were (a) The participants generally experienced a medium level of foreign language reading anxiety, (b) the participants' FLRAS level significantly increased first and then significantly decreased during the period, (c) the students' FLRAS scores were significantly negatively correlated with their reading performance at the three time points, (d) the students' FLRAS scores generally significantly negatively predicted their reading performance measured at the same time but not at a later time point, and (e) the students' reading performance did not predict their FLRAS levels. These findings indicate that anxiety is an important factor affecting students' reading comprehension in a second/foreign language.