Objective: to systematically review evidence on the administration of progesterone after a traumatic brain injury in adults and its relationship with mortality and neurological head prognosis. Inclusion criteria: randomized clinical trials that include: patients older than 12 years old, having had an injury (Glasgow <8), comparing the administration of Progesterone versus the control group (placebo or no administration). Methods: we searched the following databases: MEDLINE, the Central Register of Controlled Trials (CENTRAL); PubMed, HINARI, EMBASE; Cochrane Injury Group and reference list of articles. Results: there was no reduction in mortality in patients in the control group (RR 0.93, 95% CI 0.79-1.10 p = 0.41), there were no differences between progesterone and the control group in favorable or adverse neurological outcomes (RR 1.07, 95% CI: 0.97-1.17 p = 0.20, RR 0.94, 95% CI: 0.81 -1,08 p = 0.27), respectively. Conclusions: there is no evidence that the administration of progesterone after a traumatic brain injury reduces or improves neurological results, although further good quality studies are required to obtain conclusive results.