In this study, it is aimed to determine the values of middle school students and unwanted teacher behaviour and whether the effects of unwanted teacher behaviour differ according to gender and to what extent it affects science achievement. The study group of the research consisted of students at different grade levels who were studying at a public middle school in the city centre of Konya in the 2017-2018 academic year. The research was conducted with 273 students, including 124 male students and 149 female students. The research was carried out in accordance with the relational scanning model, which is a subtype of the general survey model. In the study, "Human Values Scale" developed by Dilmaç (2007) and "Unwanted Teacher Behaviour Scale" developed by Erben Keçici et al. (2013) were used as data collection tools. Research data were analyzed with SPSS 21.0 program. According to the findings obtained from the study, it was observed that the mean scores of the Unwanted Teacher Behaviour Scale sub-dimension of male students were higher than the mean scores of female students in the sub-dimension of the scale, but it was not statistically significant. When the Human Values Scale sub-dimension scores of middle school students were examined in terms of whether they differ according to gender, it was found that the mean scores of the friendship, peacefulness, and respect scale sub-dimension of female students were significantly higher than that of male students. It was determined that there is a significant negative relationship between the Unwanted Teacher Behaviour Scale score and the Science Course Achievement. It was observed that there was a significant negative correlation between the Unwanted Teacher Behaviour Scale score and the scores of responsibility, friendship, being peaceful, and respect sub-dimensions of the Human Values Scale. These results are very thought-provoking.