Unlike synchronous circuits, in asynchronous sequential circuit, the state changes occur in direct response to the change in input signal and different memory elements can change their state at different times. So, sometimes an asynchronous sequential circuit may become unstable. Due to this instability problem, designing of asynchronous circuits is difficult than synchronous circuits. However asynchronous circuits have the potential to be faster, and may also have advantages in lower power consumption, lower electromagnetic interference, lower noise and better modularity in large systems. Asynchronous circuits are an active area of research in digital logic design. The book begins with types of logic circuits. Different types of clocked storage elements are reviewed in this book. This book describes analysis of asynchronous sequential circuits with logic gates as well as SR latches. Designing of asynchronous sequential circuits with logic gates as well as SR latches is also explained with examples.