Tissue adhesives are a versatile and valuable alternative for wound closure. With fast application, the prevention of body fluid leakage and additional trauma to the wound, adhesives are desirable, especially in friable tissues. Although several options are already in the market, these present some drawbacks, namely poor adhesion in wet substrates and toxicity. Here, the main adhesives both synthetic and biomimetic, commercially available and those still in research, are analyzed with a focus on their adhesion mechanisms. At present, the strongest adhesive able to replace sutures in skin wounds is cyanoacrylate based. However it is toxic and therefore cannot be used internally. More recently alternatives have emerged, with PEG-based adhesives being biocompatible but mainly used as tissue sealants due to their low strength. The most recent approaches under development try to mimic the adhesion strategies of several organisms, such as the extensively studied blue mussels, sandcastle worms, barnacles and geckos. Although no ideal results have been achieved so far, large improvements have been accomplished in the last decade and research is reaching to a new level where the results are starting to meet the needs for medical applications.