The study aimed to investigate the mathematics achievement of eighth grade students on geometric transformation and geometric thinking levels. This research was carried out in the fall semester of 2018-2019. The sample was 88 students from two different middle schools in an urban area of Erzincan, Turkey. The survey model was used. The geometric transformation achievement test with 20 questions and the first 15 questions of the van Hiele geometric thinking test, which are suitable for the middle school student level, were administered to students at different times. SPSS was used to conduct analysis for descriptive statistics, standard deviation, percentage, mean and frequency, independent samples t test, and Pearson correlation. Pearson correlation was conducted to determine the relationship between the total scores that the students got from the van Hiele geometric thinking test and geometric transformation achievement test. While there was a significant relationship between the van Hiele geometry test and transformation geometry test, the geometric thinking levels of the students were below the expected level. There was no statistically significant mean difference between the boy and girl students across the schools.