Both Sigmund Freud and Melanie Klein recognized the existence of countertransference but distrusted its clinical use. This idea was the one that prevailed until the late 1940s, when Heinrich Racker in Buenos Aires and Paula Heimann in London played decisive roles in reinstating countertransference. More specifically, both Racker (in 1948) and Heimann (in 1949), independently of and without contact with each other, claimed the importance of countertransference for signifying the transference and unconscious processes that the patient re-enacts in the analytic relationship. The context in which their ideas were developed allows us to recognize differences within their common view of countertransference as a useful tool in psychoanalytic work. In this article, we present the development of both Racker’s and Heimann’s ideas on countertransference and attempt a comparison of similarities and differences of those ideas and put them into a historical and clinical-theoretical context.