Failure to thrive (FTT) is one of the most important causes leading to compromised immunity against infection, impairments of growth and weight gain, and psychomotor retardation among young children. FTT is surprisingly not uncommon in developed countries. Most cases of FTT are resulted from inadequate food or unbalanced nutritional intake, such as zinc deficiency. Zinc, as a multipurpose trace element, is involved in numerous aspects of cellular metabolism. Zinc also plays important roles in nucleic acid metabolism, cell replication, tissue repair and growth, as well as antioxidant and anti-inflammatory properties. Low zinc levels could be seen in inherited disorder such as acrodermatitis enteropathica, or acquired conditions including inadequate nutritional intake, malabsorption, excessive loss of zinc, or a combination of these factors. Zinc deficiency may be associated with growth retardation, dermatitis, alopecia, compromised gonadal function, susceptibility to infections, delayed wound healing, and even growth hormone (GH) resistance during the treatment of GH deficient children. Zinc is primarily an intracellular ion and is not as readily detectable as iron. However, measurement of the serum zinc/copper ratio is still considered to be the most reliable means of diagnosing zinc deficiency. Many researches have proven the effect of zinc on growth and development in terms of anthropometric measurements and biochemical parameters. When facing a child with nutritional FTT, it is reasonable to provide zinc replacement both for those with zinc deficiency, and this approach may take longer period of time(e.g., at least 6 months) with higher doses to be proven more efficacious.