Lumbar puncture (LP) is a procedure frequently performed by internists. The aim of this article is to describe in detail the procedure, to give some practical advices to always succeed in doing a lumbar puncture and to discuss the most frequent complications, how to prevent them and how to treat them. We will also answer some frequently asked questions, such as indications to perform neuroimaging before a lumbar puncture, or patient mobilisation after LP. Knowledge of these points is key to give a complete information to the patients and obtain an informed consent.