MicroRNAs (miRNAs) have emerged as critical regulators of gene expression by 
modulating numerous target mRNAs expression at posttranscriptional level. 
Extensive studies have shown that miRNAs are critical in various important 
biological processes, including cell growth, proliferation, differentiation, 
development, and apoptosis. In terms of their importance, miRNA dysfunction has 
been associated with a broad range of diseases. Increased number of studies have 
shown that miRNAs can functionally interact with a wide spectrum of 
environmental factors (EFs) including drugs, industrial materials, virus and 
bacterial pathogens, cigarette smoking, alcohol, nutrition, sleep, exercise, 
stress, and radiation. More importantly, the interactions between miRNAs and EFs 
have been shown to play critical roles in determining abnormal phenotypes and 
diseases. In this paper, we propose an outline of the current knowledge about 
specific roles of miRNAs in their interactions with various EFs and analyze the 
literatures detailing miRNAs-EFs interactions in the context of various of 
diseases.