This paper is aimed at describing the discourse in the mathematics classes of six teachers in three types of primary schools in Malaysia. The interest in their instructional discourse and classroom talk has arisen from the fact that the official language of instruction for the mathematics subject is English, the second language, (or possibly third language) of both the teachers and pupils. This is a widespread phenomenon in public schools in Malaysia. In the discourse of 12 mathematics classes videotaped for analysis, the main findings of the study show that teacher talk dominates student talk and mathematics talk dominates non-mathematics talk to a large extent. The use of English far exceeds the use of pupils’ mother tongue in all the classes observed except for two weak classes in the Chinese Vernacular School in which Mandarin is the dominant language recorded. However English functions more significantly with contextual Discourse rather than conceptual Discourse. There is also some association between English and procedural and regulatory Discourses. The paper concludes with implications for primary school mathematics instruction especially from the aspect of language use within a bi/multilingual context.