Spirometry is a simple test, which has a central role in the early diagnosis and management of diseases that are very prevalent and may become symptomatic late in their evolution. This manuscript explores all the necessary steps for an optimal use of spirometry (choice of equipment, quality control, technique, and interpretation). Spirometry is easy to perform in a primary care setting and its use should be encouraged among primary care physicians. We discuss the indications of this test in the follow up of patients and cover the situations that need referral to the specialist.