In this study I review the subject of biological rhythms in scorpions. This will include only some of the diel rhythmic endogenous physiological functions and not the locomotory rhythmicity, which will be dealt separately. Most studies reported here were conducted on 13 scorpion species that were studied in 39 different studies. Most of these (66.7%) were studies on a single species (Heterometrus fulvipes). Being a scorpionid, it sits and waits near its burrow not being very active, especially the females. The fact that experimenting was carried out irrespective of species diversity, gender, ecological or physiological conditions, and was usually done on animals kept in captivity for some time before the experimenting had started, is a major drawback to this kind of study. Although the main conclusion appears to be that enzymes reached their peak activity at 20.00 h, there are some exceptions showing otherwise that need further study in order to explain them.