There is increasing evidence that vitamin D regulates immune responses. There is also epidemiological evidence of a relationship between vitamin D deficiency and development of asthma. In addition, several epidemiological studies suggest that low levels of vitamin D during pregnancy and early life are inversely associated with the risk of developing respiratory infections and wheezing in childhood. Vitamin D also seems to reduce asthma exacerbation and increase the response to glucocorticoids. These findings have led to considering a possible link between the occurrence of allergic respiratory diseases and low levels of vitamin D. However, the precise role of vitamin D in the pathogenesis of asthma still remains unclear, emphasizing the need for well-designed trials on vitamin D supplementation to decipher its role in preventing and/or managing the disease. This review examines the relationship that exists between vitamin D deficiency and childhood wheezing and asthma.