In this article we have summarized the basic information which identifies several key issues in the study of perireceptor and receptor events in vertebrate olfaction. We have emphasized the biophysical and biochemical data which have established a pivotal role for the olfactory mucus in the access of odorants to receptor sites as well as their clearance from the micro-environment. In addition, based on initial reports in the literature, we have postulated that the uptake of odorants by cells in the olfactory epithelium and their subsequent enzymatic degradation is an important mechanism in odorant removal. Hence, the pre- and post-interactive events in vertebrate olfaction play a key role in molecular recognition, sensory transduction and receptor desensitization. Study of the primary events in vertebrate olfaction is an increasingly active area of research in neurobiology. Application of contemporary techniques in cell and molecular biology as well as biochemistry and cellular biophysics is yielding new insights into the process and into establishing new hypotheses to be tested.