Genetically modified organisms (GMOs) are one of the hottest socio-science topics that has become increasingly popular in recent years. With new knowledge and advances in the field of biotechnology and the expansion of the spectrum of their use, GMOs are an interesting topic not only for scientists, but also for the general public and the media. However, the problem that many researchers have noted is that public awareness and knowledge of GMOs and biotechnology in general is very low. Most studies have also concluded that those with more knowledge tend to have a more positive attitudes towards GMOs. The aim of this study was to examine the knowledge of, attitudes towards and acceptance of GMOs among students of various science courses (biology, biotechnology, microbiology) and among pre-service teachers. We conducted a first survey among the students, then organised a lecture on GMOs for them and later conducted a second survey among the same students. We found that there are differences in knowledge of, attitudes towards and acceptance of GMOs among students of different courses. The students of the science courses had more knowledge than pre-service teachers. As expected, biotechnology students showed the most positive attitudes and the highest degree of acceptance of GMOs, while pre-service teachers showed the lowest level of acceptance. The positive correlation between knowledge and attitudes and between knowledge and acceptance of GMOs was confirmed. After the lecture, the differences in knowledge decreased and acceptance of GMOs in general raised, whereas attitudes remained almost the same.