370 Purpose: Neutropenia is not uncommon in solid organ transplant patients and its etiology is multi-factorial. The purpose of this study was to evaluate the impact of G-CSF on outcomes in this setting. Methods: All patients who received at least one dose of G-CSF between 01/01/97 and 07/31/97 were identified. The indications, dose, duration of G-CSF, concurrent medications, laboratory data, infections during and 6 months after G-CSF therapy, rejection post-G-CSF administration, graft function, and patient survival were collected. Results: Twenty-one patients (10 kidney, 6 kidney-pancreas, 3 pancreas, and 2 liver) experienced 36 episodes of neutropenia and received G-CSF. The time to the first dose of G-CSF was 506 days post-transplant (33 to 2190 days) with 57% of patients treated within 6 months. Neutropenia was related to cancer chemotherapy in 4/36 episodes (12.5%), CMV in 22/36 (61%), and concurrent bacterial and/or fungal infection in 14/36 (39%). Concurrent causative medications included ganciclovir 27/36 (75%), mycophenolate mofetil 20/36 (56%), H2-blockers 19/36 (53%), sulfamethoxazole/ trimethoprim 16/36 (44%) and azathioprine 1/36 (3%). The mean dose of G-CSF administered was 4.54±1.0 μg/kg/day with a mean duration of therapy of 7.1±6.1 days. Medications contributing to neutropenia were adjusted or withheld until the ANC exceeded 2000/mm3. The mean ANC at the beginning and at the end of G-CSF therapy was 970±604/mm3 and 6766±5848/mm3, (p ≤ 0.001). Within 6 months of G-CSF treatment, 8 patients had recurrence of CMV infection and 10 patients had recurrence of bacterial infection. Nine patients required retreatment with G-CSF within 3 months. The mean duration of follow-up for rejection after the first dose of G-CSF was 313 days (1 to 630 days). Four patients (19%) had biopsy proven rejection, 3 within 6 months and one 9 months after G-CSF. Among the patients who experienced rejection, 2 had CMV infection, 1 had Ehrlichiosis requiring reduction in immunosuppression. Patient survival was 76% (16/21). 3 patients died while receiving G-CSF and the remaining 2 patients died 1 and 4 months after G-CSF. Two patients died of underlying malignancies and 3 died of bacterial and fungal infections (2 Aspergillus, 1 C. Albicans). Conclusion: The use of G-CSF in conjunction with pharmacological modification was successful in reversing neutropenia. The benefits of G-CSF in reducing the incidence of infection and improving patient survival requires further study.