This systematic review update summarizes evidence concerning transfusion-transmissible infections (TTIs) in male blood donors reporting sex with another man (MSM) or after easing the MSM deferral period. We searched five databases, including studies comparing MSM versus non-MSM donors (Type I), MSM deferral periods (Type II) or infected versus non-infected donors (Type III) in Western countries, and used GRADE to determine evidence certainty. Twenty-five observational studies were included. Four Type I studies suggest that there may be an increased risk for overall TTIs, human immunodeficiency virus (HIV), hepatitis B virus (HBV) and syphilis in MSM donors, but the evidence is very uncertain. There was insufficient evidence of MSM with low-risk sexual behaviour. A Type II study indicates that easing the MSM deferral period to 1 year may have little to no effect on TTI risk. TTI prevalence in blood donors under 5-year, 1-year, 3-month or risk-based deferral in eight other Type II studies was too low to provide clear conclusions on the effect of easing the deferral. Three Type III studies reported that MSM may be a risk factor for HIV. Increased risk of HBV, hepatitis C virus and HTLV-I/II could not be shown. The evidence from Type III studies is very uncertain. There may be an increased risk of HIV in MSM blood donors. Shortening the deferral from permanent to 1 year may have little to no effect on TTI risk. However, there is limited, unclear evidence from observational studies concerning the impact of introducing 3-month or risk-based deferrals.