Toxins are thought as villains as they cause death and debilitation. In reality, they have contributed more to improving our lives than cause death. Toxins have played crucial roles in the discovery and development of therapeutic and diagnostic agents for human diseases. They have also contributed as important research tools and helped us to understand molecular mechanisms of normal physiological processes such as neurotransmission, blood coagulation and platelet aggregation. Our lab has been studying structure-function relationships and mechanism of actions of novel toxins from various sources. Our research has contributed to both basic and applied sciences. Based on the functional sites of the toxins, we have developed a number of therapeutic agents for various human diseases. I will describe the role of careful, keen and systematic observations in distinct lines of research straddling both basic and applied research.