This paper reviews some experimental methods used in the study of genetic fixed behaviour, some examples of investigations in farm animals as well as some results of the author's studies on the emotionality in pigs are given. Many investigations have been made on the estimation of heritability of behaviour patterns in cattle, pigs, poultry and dogs. Behaviour patterns such as temperament, aggressiveness, and nervousness showed relatively high h2-values; other behaviours like trainability, emotionality, and pre-laying showed relatively low values. Selection experiments were carried out in poultry and dogs. The results showed that after a few generations remarkable differences in behaviour patterns between the new lines and the original populations were obvious. Besides the selected traits, modifications occurred in other behaviour patterns and in physiological responses. The emotionality in pigs was investigated with the open field test in 3 genetic groups: German Landrace (DL), Duroc (DU), and cross-breeding between these breeds (DU x DL). Increasing emotionality was displayed by increasing ambulatory activity and vocalization. The lowest activity was observed in the pure breeds, DU showed less signs of emotionality than DL, whereas DU x DL showed the highest of emotionality.