e19225 Background: IVIG is used to replenish immunoglobulins in HG due to hematologic malignancies (HM) or their treatment (stem cell transplantation (ASCT) and chimeric antigen receptor T-cell therapy (CAR-T)), in an effort to reduce the risk of infections. There is limited high-level evidence to support this use, and IVIG supplies are limited with a recent shortage leading to restricted allotments. We report the results of a stewardship program designed to safely reduce IVIG usage. Methods: An IVIG stewardship plan (ISP) was implemented with the following requirements for IVIG administration: IgG level < 400 mg/dL (corrected for paraprotein) for post-ASCT and post-CAR-T patients, or IgG < 400 mg/dL with evidence of a bacterial infection within the last 3 months that required hospitalization or an emergency department encounter for those with HM. We evaluated the amount of IVIG administered, the incidence of infections, and antibiotic administration before and after implementation of an ISP. Results: In the 3 months pre-ISP, HG accounted for 38% (72/188) of total IVIG orders. 86 pts received IVIG for HG in the 3 months pre-ISP. The amount of IVIG given decreased from 1907 g/month pre-ISP to 670 g/month post-ISP; estimated cost savings in IVIG was $57,561/month. The pre-ISP median IgG level prior to dosing of IVIG was 550 (range 40-1189) mg/dL. Compared to pre-ISP, pts who stopped receiving IVIG post-ISP had lower median pre-dose IgG (444, range 93-819 mg/dL, p<0.05), infections/patient-months (14/141 vs 56/255, p<0.001), antibiotic usage (12/47 vs 44/86, p<0.05), and hospitalization rate for infection (4/55 vs 21/86, p<0.05); no deaths occurred. For those receiving IVIG post-ISP, adherence to guidelines was 64%. Compared to pre-ISP, median pre-dose IgG was lower (328, range 51-1011 mg/dL, p<0001), infections/patient-months decreased (27/163 vs 56/255, p<0.001), and antibiotic usage, hospitalization rate for infection, and deaths from infection all remained stable. Conclusions: An ISP for HG led to a dramatic and sustainable decrease in IVIG usage, primarily by selecting out patients who are low risk for infection after discontinuation of IVIG. Such an ISP is replicable and warrants adoption.