Respirable particles cause many occupational and environmental diseases of the lung. To study these diseases, laboratory animals are often exposed to these particles. Inhalation and instillation are the well-known techniques for experimental exposures of the lung to respirable particles. Recently, another technique called oropharyngeal aspiration (OPA) has been introduced for exposing the lung to pathogens and/or particles. The conventional OPA technique for the mouse is generally carried out using a micropipette with a fixed slant board. In order to modify the conventional OPA in this study, anesthetized mice were placed on an adjustable slant board, a syringe pump was used to deliver the solution to the oropharynx, and the mice were allowed to recover in vertically positioned tubes for 6 minutes until fully awaked. Most importantly, the whole process of OPA could be carried out simply by an examiner. This modified OPA technique was validated by exposing the mouse lung to Evans Blue dye with a success rate of 95%.