Improvisation is considered an increasingly relevant topic for organizations, especially for those that act in volatile and unstable environments (Crossan and Sorrenti, 1997; Weick, 1998; King and Ranft, 2001). We considered to study improvisation in medical practice since it is believed to be “an art and a science” (Haidet, 2007; Saunders, 2000), and it embeds much improptu, as it requires the adaptation of behaviours and performances. Despite the high level of regulations, medical practice presents some characteristics make it an interesting context to study, observe and analyse improvisation. The paper deals with critical case where the manifestation of improvisation allowed the researchers to replicate or expand the existing theory (Eisenhardt, 1989, Plowman et al., 2007). The study tried to answer to the following research question: How does improvisation emerges in environments characterized by the existence of a large number of procedural controls? What are the conditions/circumstances that allowing improvisation? The attempt to answer such questions unveiled the existence of several artifacts.