In the study, it was researched the effect of internet-based application on student success. Internet-based application was used at the teaching of triangles subject which is included in 8th grade units of triangles and algebra. The study was carried out over the internet with a computer software program: Vitamin Program. The study was carried out with total 37 8th grade students in two separate classes in a study centre in 2011-2012 school years. It was carried out internet-based teaching material on the experiment group and also conventional teaching method and materials on the control group. In the research, “the achievement test consisting of triangles subject” was carried out as a data collection tool in pre-test and post-test both groups. As a result of the research, success grade of experiment group which was carried out internet-based application applied with Vitamin Program is higher than success grade of control group in which was used conventional teaching method. In consequence of the study, it was suggested that internet-based teaching programs, which call and attract students’ attention must be used in a more frequent way.