This special issue is focused on acetylcholine to mark the hundredth year since its discovery by Dr. Henry Hallett Dale. Some readers may be of the opinion that the available literature on acetylcholine is quite vast and, therefore, there is no scope for more interesting findings. However, when we consider the significance of its physiological roles and discuss its involvement in many severe diseases, acetylcholine remains an intriguing molecule worth to be kept in mind.