This study aimed to examine mathematics teachers' integration of Mathematics Analysis Software (MAS) in the teaching of mathematics at upper secondary school classrooms. It employed a qualitative approach with classroom observations and interviews for the data collection. The study was carried out in Indonesia, and the participants were ten mathematics teachers from ten secondary schools. The finding suggested that the participants failed to take advantage of pedagogical opportunities to digital technology in facilitating students' knowledge construction. In addition, this study revealed that the instructional practices with technology at classroom and subject levels were closely related to the type of tasks they set in their lessons. Moreover, the findings indicate that it is important for mathematics teachers to set technology-rich mathematics tasks for students to fully capitalized pedagogical opportunities of Mathematics Analysis Software.