VNTR (variable number of tandem repeat) markers, also called single-copy minisatellites, were originally isolated from human DNA as highly informative restriction fragment length polymorphisms for mapping purposes. Evidence has lately emerged that some VNTR sequences play significant roles in the regulation of transcription, and that some may also influence the translational efficiency or stability of mRNA, or modify the activity of proteins by altering their structure. Some apparent associations of VNTR sequences with personality traits or with susceptibility to diseases have strengthened the likelihood that these tandemly-repeated genomic elements are of physiological and biological importance. In this review, we summarize recent progress in efforts to clarify mechanisms involving VNTR sequences.