Human umbilical cord-derived mesenchymal stem cells (hUC-MSCs), isolated from discarded extra-embryonic tissue after birth, are promising candidate source of mesenchymal stem cells (MSCs). Apart from their prominent advantages in abundant supply, painless collection, and faster self-renewal, hUC-MSCs have shown the potencies to differentiate into a variety of cells of three germ layers (such as bone, cartilage, adipose, skeletal muscle, cardiomyocyte, endothelium, hepatocyte-like cluster, islet-like cluster, neuron, astrocyte and oligodendrocyte), to synthesize and secret a set of trophic factors and cytokines, to support the expansion and function of other cells (like hematopoietic stem cells, embryonic stem cells, natural killer cells, islet-like cell clusters, neurons and glial cells), to migrate toward and home to pathological areas, and to be readily transfected with conventional methods. Two excellent previous reviews documenting the characteristics of this cell population with special emphasis on its niche, isolation, surface markers and primitive properties have been published recently. In this review, we will firstly give a brief introduction of this cell population, and subsequently dwell on the findings of differential capacities with emphasis on its therapeutic potentials.