This study aims at investigating the barriers encountered by science teachers in laboratory activities in Rwandan teacher training colleges (TTCs) using questionnaires and interviews. The results confirmed that teachers face barriers like time limitation, material scarcity and lack of improvising skills in their everyday science teaching life. About 95% of teachers who teach in schools with laboratories and only 5% of their peers at schools without laboratory show enough awareness on science laboratory activities. However, in terms of the importance of laboratory experiment and improvisation approach, students had the similar responses in all the investigated schools.