Macrophages are widely distributed in the body. Macrophages express a variety of receptors, and use these receptors to engage and respond to a wide range of microbial and chemical molecules. The physical and physiological environments of the macrophages influence their phenotype and their biology. Lung macrophages (alveolar, airway, interstitial, and intravascular) are classified based on their physical location. The alveolar macrophage is the most intensely studied among the lung macrophages because of ease of its isolation for in vitro studies, which are conducted in an environment drastically different from their surfactant-rich in vivo milieu. The challenges of in situ identification of interstitial macrophages, and the difficulties of their isolation for in vitro studies have resulted in very little and confusing data on their biology. Pulmonary intravascular macrophages (PIMs), constitutively found in cattle, sheep, goat, horses, and pigs, have critical roles in lung inflammation and are of unique significance for veterinary immunology. PIMs are induced in species such as dogs and rats, which don't have them constitutively. The talk will focus on the current state of the knowledge, gaps in our knowledge, and some strategies for future studies of lung macrophages in domestic animal species.