The purpose of this study is to investigate the effect of probability teaching with the argumentation approach on the academic achievement of pre-service mathematics teachers and the permanence of probability knowledge. Quantitative research method was adopted in the study and quasi-experimental design was used. The study group consisted of 44 pre-service teachers studying in the third grade of Elementary Mathematics Education at a state university. The Probability Achievement Test (PAT), which was developed by the researchers, was used to measure the academic achievement and permanence of probability knowledge of pre-service teachers. PAT was applied to pre-service teachers as pre-test, posttest and retention test. According to the findings, it was found that there was a statistically significant difference between the PAT posttest scores of the groups in favor of the experimental group. As a result of the analysis of the PAT retention scores of the groups, it was concluded that there was no statistically significant difference between the PAT retention scores. As a result of the research, it has been seen that the argumentation approach increases the pre-service teachers' success in probability more than the traditional method. On the other hand, the argumentation approach had no effect on the permanence of the knowledge of the pre-service teachers.