Some behaviours frequently observed in ridden horses indicate difficulties in adapting to their living or working conditions. We divided into three groups: stereotypies (S: cribbing, weaving, box circling), behaviours unrelated to human activity (NH: spooking, social separation anxiety), and behaviours associated with human interaction during handling, training, or riding (H: pulling on the reins, rearing, kicking, aggression during handling and tacking, refusal to approach). Previous studies have reported relationships between innate personality traits (temperament) and stereotypic behaviours. However, it remains unclear whether temperament also predisposes horses to other maladaptive behaviours. The aim of this study was to determine whether performance horses exhibiting such behaviours differ in levels of fearfulness, sensitivity, and energy compared with horses that do not exhibit them. Preliminary results are presented. Data were collected through an online survey addressed to equestrian competitors in Poland and the Czech Republic. Respondents reported the occurrence of S, NH, and H behaviours in their horses and rated fearfulness, sensitivity, and energy on a 7-point scale. A score of 1 indicated very fearful, highly sensitive, and low-energy horses, while 7 indicated not fearful, not sensitive, and highly energetic horses. Responses for 467 horses were analysed. The distributions of variables did not follow the normal distribution, thus, non-parametric test were used. Differences in temperament traits between groups were tested using the Wilcoxon two-sample test. Spearman’s correlation was used to assess relationships between temperament traits. Temperament traits were only weakly correlated (r < 0.2), indicating their relative independence. Horses displaying stereotypies (3.00%) did not differ significantly in any temperament trait compared to horses without such behaviours. In contrast, horses showing NH (8.06%) and H behaviours (19.06%) were rated as more fearful (P < 0.01 for NH and H) and more sensitive (P < 0.01 for NH and P < 0.01 for H) than those not exhibiting maladaptive behaviours. Energy level was not associated with the occurrence of these behaviours. The incidence of stereotypic horses, when owners reliably identified them, was low in our study compared with 10-40% reported previously. While the survey offers an initial insight into the topic, we can hypothesise that temperament traits may predispose fearful and sensitive horses to maladaptation and/or influence how they express difficulties in adapting to living, handling, and working conditions. NH behaviours may reflect increased fearfulness and sensitivity and should be considered during daily handling and riding. Since behaviours such as aggression or resistance during handling may be linked to pain, more fearful and sensitive horses may express H behaviours more readily and more overtly, making them more likely to draw attention to their maladaptation. The authors confirm that the work described in this abstract conforms with the ISAE Ethical Guidelines.