The use of live animals in instruction plays an important role in biological education, with the intention that attitudes and emotions should be positively influenced. To date, studies in this field have given mixed results, and there has certainly been a lack of studies on student attitudes and knowledge of poisonous and venomous animals. This study focuses on the effect of the use of poisonous and venomous animals in biology instruction. Two treatment groups of Slovenian seventh and eighth graders (N = 123; age 12.3 and 13.2 years, respectively) were compared. The experimental group (N = 82) was given the opportunity to observe with adequate risk assessment live animal species. The observation of live poisonous and venomous animals led to higher values on different attitudinal dimensions. After instruction, we found no differences between both treatment groups in knowledge. Interest in learning about the different poisonous and venomous animals increased significantly. The level of disgust decreased for the viper, spider, and scorpion. However, 'fear' seems to be more stable and less influenceable than 'disgust'. We recommend that students should be offered as many first-hand experiences with live poisonous and venomous animals as possible mainly through informal learning environments, such as zoos.