As the postgenomic era continues to unfold, a new wave of scientific investigation is upon us focusing on the application of genomic technologies to study the meanings encrypted on the DNA code and the responses of living organisms to changes in their environment. Recent functional genomics studies in this laboratory have focused on the role of the aryl hydrocarbon receptor, a ubiquitous transcription factor, in genetic programming during renal development. Also of interest is the application of genomics investigations to the study of chronic medical conditions associated with early life exposures to environmental contaminants. Molecular evidence is discussed in this review within the framework of human molecular medicine.