Undesirable and stereotypical behaviors may indicate abnormalities in the living environment of animals. They have a negative impact on the welfare of animals and hinder the handling and use thereof. Unfortunately, horse owners often fail to recognize the causes of behavioral problems in their animals. The aim of the study was to analyze the living conditions, type of use and individual characteristics of horses (age, sex, breed, and temperament) in relation to displaying undesirable and stereotypical behavior. The assessment was made based on 609 online questionnaires completed by horse owners from Poland (n=376), UK (n=145), USA and Canada (n=66), Australia and NZ (n=22). Undesirable and stereotypical behaviors were exhibited by 36,1% and 31,9% of the horses, respectively. It has been shown that the undesirable behaviors are influenced by e.g. access to pastures, presence of other horses on paddocks and supply frequency of roughage. The type of use of the animal was not found to be associated with behavioral problems. Referring to the individual characteristics of horses, it has been found that only temperament has an impact on the occurrence of problematic behaviors. Both undesirable and stereotypical behaviors are particularly frequently displayed by animals with a lively temperament. Horses should be kept under conditions meeting their feeding, social and locomotor behavioral needs. The evaluation of their individual traits may help to assess the risk of developing abnormal behavior and thus, to prevent it. Raising the awareness of horse keepers and breeders of the causes of problem behaviors should be an important issue.