In this study, the effects of computer-assisted laboratory applications on pre-service science teachers' attitudes towards science teaching were investigated and the opinions of the pre-service teachers about the application were also determined. The study sample consisted of 46 students studying science teaching Faculty of Education. The study data were obtained after students participated in an eight-week computer application embedded in the margins of the course "Laboratory Applications for Science Teaching II". Explanatory design, which is a mixed method research design, was used in the study. The quantitative data in the study are collected by using attitude scale and the qualitative data are collected via semi-structured interview form. For the analysis of the quantitative data, paired sample t-tests and bar graphics were used. For qualitative data analysis, content analysis was made. The results reveal that computer-assisted laboratory applications had a significant effect on pre-service teachers' attitudes towards science teaching. Moreover, the pre-service teachers defined the simulations as useful applications. They also indicated that the simulations were effective for their learning, supported their knowledge, and affected their attitude and motivation towards the lesson in a positive way. They also defined the characteristics they expected from simulation programs as being easy to use and enjoyable, and concretizing the information and developing creativity.