With the objective of determining the association between bacteremia and transoperative antegrade mechanical lavage of the colon in an experimental model of obstruction of the left colon in rats, 40 male Wistar rats aged between 90 and 120 days were divided randomly into four groups: A, with intestinal obstruction and with mechanical lavage of the colon; B, with intestinal obstruction and without mechanical lavage of the colon; C, without intestinal obstruction and with mechanical lavage of the colon; and D, without intestinal obstruction and without mechanical lavage of the colon. Analysis of the results showed that there was no bacteremia in the animals in the sham group. On the other hand, bacterial growth in blood cultures was found in three animals (30%) in group C and in four animals (40%) in group B. Positive blood culturing was presented by eight animals (80%) of the rats in group A, and variance analysis on this finding was statistically significant (p = .0029). It can be concluded that, in this experimental model, intestinal obstruction causes a fourfold increase in the risk of bacteremia, while lavage causes an almost threefold increase in the chance of bacterial dissemination into the blood stream. This explains why there was greater incidence of bacteremia in the animals with obstruction and with lavage.