The transplantation of allogeneic hematopoietic stem cell (HSCs) has been a successful therapy for a variety of malignant and non-malignant hematopoietic diseases. Wider use of this therapy has been limited due to: lack of suitable human leukocyte antigen (HLA) matched donors; lengthy unrelated bone marrow donors search; severe graft-versus-host diseases; and high transplant-related mortality from problems such as delayed immune reconstitution. Umbilical cord blood (UCB) transplantation is currently being investigated as one strategy to address these limitations, due to an unlimited amount of UCB once it is not used after birth. Not much is know about the molecular interactions and proteins that contribute to the signaling pathways in the hematopoietic CD34+ cell, and also, there is no information about the protein profile of this cell. Thus, it seems evident that in order to understand in greater detail the physiology of the HSCs, it is necessary a complete characterization at protein level of the CD34+ cell compartment. In order to solve this question the HSCs comparative proteomic studies should be undertaken to investigating individual sample in the same physiological states, consequently, the reproducibility of the proteome pattern from individual samples may produce a real stem cell proteomic fingerprint. In the present work we compare and analyze the heterogeneity of five different samples of CD34+ cells of UCB by a proteomic approach. The HSCs CD34+ cells were enriched and, analyzed by FACS, using the Dynal CD34+ selection system (Dynal). The protein extracts, were analyzed through a high-resolution two-dimensional (2D) electrophoresis assay with the Multiphor II electrophoresis System (GE). Fifty micrograms of each sample was precipitated and used in the 2-D gels. The proteins were separated using a 11cm ImmobilineDrystrip (GE) of pH 4-7, for 78kVh. The second dimension was done in a 8-18% gradient SDS-PAGE gel in a Multiphor II (GE) apparatus. The gels were analyzed and all protein-spots were identified by Mass spectrometry in a MALDI-TOF-TOF instrument (4700 Applied Biosystems). Using this approach we identified 150 proteins present in all samples and 34 differentially expressed protein spots between the samples. Taken together these results could serve for the establishment of standard pattern of UCB and also in the generation of qualitative fingerprint from human UCB stem cells.