Background: Probiotics are living bacteria, which can be used as a food supplement to produce inhibitory agents and compete with pathogens in the guts. Nowadays, because of the easy accessibility and misuse of antibiotics, probiotic usage is increasing. The goal of our study is to assess the effects of probiotics on colorectal surgery complications. Methods: The enrolled cases were selected from colorectal surgery candidate patients, who referred to Sina and Imam Reza Hospitals of Tabriz University from April of 2016 to April of 2017. They were divided into two groups of study and control. For the study group, 7 days before surgery, one capsule of probiotics (Familact) was administrated every night, while the control group was given capsules of placebo. Results: Although the infective complications, mortality ratio and duration of hospitalization in the study group were lower than the control group, these differences were not statistically significant. Discussion: Our study confirmed that preoperative probiotic consumption in colorectal surgery had not affected complications or mortality of surgery and this finding is in disagreement with some previous studies. Perhaps, other strains of bacteria or different dosage, duration and rout of administration can have positive effects on these complications. Conclusion: This study showed that there was no correlation between probiotic consumption preoperatively and decreased complications or mortality after colorectal surgery.