Records: The effect of the tromboprofilaxis with heparin (HBPM or HNF) in patient of internal medicine has not been evaluated systematically. Methods: Analysis of studies randomized on tromboprofilaxis in patient of Internal Medicine, excluding those with Sharp Heart attack of the Miocardio or Ischemic Cerebral Illness. End points: Incidence of TVP, c1inical EP, fatal EP and adverse goods. Result: were selected five studies that corresponded to a total of 15328 patients, they compared heparin like measured tromboprofilactica with placebo, observing a non significant reduction in the incidence of Fatal Lung Embolismo (RR = 0.93 IC (0.87-1.08». There was a significant decrease in the incidence of TVP and clinical EP with the heparin use, in comparison with the controls (RRA 9% and 0.66%) and a NNT 11and 151 patients, respectively. it was evidences a significant increase in the incidence of more Hemorrhage in the heparin group (RR = 1.47 IC (1.22-1.73). Conclusion: This metaanalisis showed that the tromboprofilaxis with heparin (HBPM or HNF) reduced the incidence of TVP and c1inical EP, without any significant effect in fatal EP.