This study explored the efficacy of intravenous immunoglobulin (IVIG) prophylaxis in reducing infection-related hospitalizations (IRHs) in MM patients. This was a retrospective study of MM patients who received IVIG at Taussig Cancer Center between July 2009 and July 2021. The primary endpoint was rate of IRHs per patient-year on-IVIG versus off-IVIG. 108 patients were included. There was a significant difference in the primary endpoint of rate of IRHs per patient-year on-IVIG versus off-IVIG in the overall study population (0.81 vs. 1.08; Mean Difference [MD], -0.27; 95% Confidence Interval [CI], -0.57 to 0.03; p value [P] = 0.04). The subgroup of patients with a 1-year period of continuous IVIG (49, 45.3%), the subgroup with standard-risk cytogenetics (54, 50.0%) and the subgroup with 2 or more IRHs (67, 62.0%) all showed a significant reduction in IRHs while on-IVIG versus off-IVIG (0.48 vs. 0.78; MD, -0.30; 95% CI, -0.59 to 0.002; p = 0.03) and (0.65 vs. 1.01; MD, -0.36; 95% CI, -0.71 to -0.01; p = 0.02) and (1.04 vs. 1.43; MD, -0.39; 95% CI, -0.82 to 0.05; p = 0.04) respectively. IVIG showed significant benefit in reducing IRHs in the overall population and in multiple subgroups.