Introduction:Haematopoietic stem cell transplantation (HSCT), also known as bone marrow transplantation (BMT), is being increasingly used for pathologies such as like leukaemia, lymphoma, and multiple myeloma, as well as other haematological abnormalities. Risks include infection, graft-versus-host disease, and graft failure. The stem cells are collected using apheresis and stored for transplantation. Mobilizing agents like cytokines, chemokines, and small molecules help release stem cells into the blood. Poor mobilization can lead to complications. The decision to undergo HSCT depends on the patient's condition and healthcare team's advice. We undertook this study to find out the efficacy of G-CSF alone versus a combination of G-CSF and Plerixafor (administered 6-8 hours before harvesting) in poorly mobilizing CD34+ individuals. Materials and methods: It was an observational study, data was collected from two transfusion medicine department (Medical College , Department of IHBT and NSH, Howrah, Department of Transfusion medicine) and retrospectively analysed using DATAtab online software. informed consent was obtained from the participants. A total thirty-six autologous and ten 6/6 HLA matched sibling allogenic peripheral blood haematopoietic stem cell (PBSCs) transplant recipients (aged 5- 60 years) were analysed from records during the period of 2016 to 2023. All of them were haemato-oncological patients and refractory to chemotherapeutic agents or not responding to conventional treatment. Efficacy of G-CSF alone versus a combination of G-CSF and Plerixafor (administered 6-8 hours before harvesting) in poorly mobilizing CD34+ individuals. The observed values for engraftment as absolute neutrophil count (ANC) in both the groups were compared by using different statistical parameters in DATAtab software. ‘p’ ≤ 0.05 value was considered as significant.Results:N group was found to have higher values for the dependent variable neutrophil engraftment (Mdn = 11) than the Y group represent G-CSF used CD34+ mobilisation along with single dose plerixafor (Mdn = 10). The difference between N and Y with respect to the dependent variable neutrophil engraftment (ANC≥500µl) was statistically significant, U=104.5, p=.018, r= 0.38. 0 group (without cryopreservation) has higher values for the dependent variable neutrophil engraftment (N) (M = 11.57, SD = 2.36) than the 1 group (with cryopreservation) (M = 11.23, SD = 2.39). The results of the descriptive statistics show that the autologous PBSC transplant group has lower values for the dependent variable absolute neutrophil engraftment (M = 10.45, SD = 0.83) than the allogenic PBSC transplant group (M = 15.22, SD = 2.44). the difference between auto and allogenic with respect to the dependent variable was statistically significant, t(8.51) = -5.78, p = <.001, 95% confidence interval [-6.65, -2.88]. Conclusion: G-CSF plus plerixafor mediates faster engraftment as compared to Single dose G-CSF and the difference is found to be statistically significant.