The definition of recklessness has become one of the contentious subjects in English criminal law since the beginning of the 20th century. The subjective meaning based on foresight of risk, given by R v Cunningham, has been overruled by the House of Lords in R v Caldwell and has been submitted the definition depending on the objective approach. Accordingly, the dichotomy on the definition of recklessness has been created. The discussion starting these two cases was legally terminated by the R v G & G case in 2004, but issue on the meaning of recklessness has been maintained by the academics. In this regard, the purpose of this paper is to discuss the notion of recklessness in Criminal law under the three tests given by above cases and to compare recklessness and gross negligence in cases of involuntary manslaughter.