Antisense oligonucleotides are short pieces of synthetic, chemically modified DNA or RNA that are designed to interact by Watson-Crick base pairing with mRNA encoding a targeted protein. During the past 20 years the technology associated with the development of antisense has improved dramatically, and emerging chemistries have made antisense oligonucleotides into powerful and versatile tools to study the function of proteins in living cells. The dramatic increase in novel genomic sequence information that has recently become available has generated enormous opportunities for the development of antisense oligonucleotides capable of altering the expression level of virtually any gene. With this will come a nearly equal opportunity to determine the role of individual proteins in a vast array of cardiovascular disease. The great specificity that these compounds exhibit in vitro suggests that they may also have an exciting future for development into therapeutics useful for the treatment of human disease. This review highlights some of the advances made in the field of antisense research, placing an emphasis on uses and proper controls.