Neural Networks have become standard solutions in many real-life relevant applications, such as healthcare. Yet, their vulnerability to backdoor attacks is a concern. These attacks modify a small portion of the data or the model to insert hidden triggered behaviors. Neuro-symbolic (NeSy) models, which integrate neural networks with symbolic reasoning, have been proposed as more robust and explainable AI models. However, their resilience against backdoor attacks has not been examined. This research investigates the robustness of Logic Tensor Networks (LTNs), representative NeSy models, against BadNet attacks, a simple and stealthy class of data poisoning backdoor attacks. Through empirical evaluations, we analyze how LTNs are affected by a bigger focus on symbolic reasoning and in different settings of an LTN model and BadNet attack, we measure the attack success rate (ASR). Our findings aim to provide a first insight into the vulnerability of NeSy systems to backdoor attacks.