Today, higher education students largely behave unethically if they see an opportunity to do that and if they feel they can control their behaviour. Higher education institutions are faced with this problem and in most cases, they do not resort to any "penalties", restrictions and other measures that would reduce the unethical behaviour of the students. Students' unethical behaviour is the result of marry influencing factors. Theory of planned behaviour is used in this paper to determinate which factor(s) have the highest influence on student's unethical intentions and behaviour. The aim of the study was to see if there is a statistically significant difference between factors of the theory of planned behaviour (personal attitudes, subjective norms, perceived behaviour control) and students' intentions of unethical behaviour. The research was conducted on a sample of 622 university students (undergraduate and graduate). Descriptive analysis, multivariate analysis (reliability analysis, cluster analysis, linear regression and correlation analysis) and analysis of variance (ANOVA) were used in the data processing and analysis. The results show a statistically significant positive correlation between the three observed variables of the theory of planned behaviour (personal attitudes, subjective norms, perceived behaviour control) toward unethical behaviour and their future intentions toward unethical behaviour. More than half of the students who were cheating in high school cheat at university as well. A quarter of the respondents behave unethically if they find an easier way to solve the colloquium/exam or use other, unethical methods when writing seminar or graduate paper. All this leads to the fact that the control by the university/faculty is not at a level that would solve these problems and thus reduce the students' future intentions for unethical behaviour.