Aim: This study examines the effect of teacher talk and interaction on students' achievement in Tabriz high schools. Methods: This research was a descriptive and correlation study. Sixty teachers and 800 students by multistage random sampling are selected for study. For gathering data, the observation method based on Flanders interaction analysis categories was used. The validity of the instrument was approved by Flanders and other researchers. The reliability of the Flanders interaction analysis was measured by inter-observer agreement ranged from 0.85 to 1.00. Result: The results showed an independent t-test revealed no significant difference between male and female talk and teaching style. A one-way ANOVA revealed a significant difference in praises or encouragements in teaching mathematics, empirical sciences, and humanities. Conclusion: Humanities teachers encouraged students more than those of mathematics and empirical sciences. In addition, the direct teaching is negatively correlated with students' achievement.