Teacher immediacy behaviour is the factor that have found strong association with students' learning outcomes. Although, both the verbal and nonverbal form of immediacy behaviour has been found association with students' learning, nonverbal immediacy behaviour is considered more important in students' learning than the verbal immediacy behaviour. The present study analysed the nonverbal immediacy behaviour of the mathematics teachers in secondary schools of West Bengal, and investigated its' impact on teachers' effectiveness. Necessary data were collected by using Nonverbal Immediacy Behaviour Scale and Teacher Effectiveness Scale. A total 1303 tenth graded students from 120 classes randomly selected to give response about their mathematics teachers. Results of the study indicate that there is no significant difference among the male and female teachers in their pattern on immediacy behaviour. The findings also indicate that nonverbal immediacy behaviour has a significant impact on mathematics teachers' effectiveness.