Chronic obstructive pulmonary disease (COPD) is a major worldwide health problem. There exists a relationship between COPD and increased oxidative stress, and oxidants may be involved in lung damage during the course of COPD. Polymorphonuclear (PMN) cell recruitment at lung level plays an important role in free radical overproduction, impact inflammatory processes and may alter oxidant-antioxidant balance. Biological aging is thought to be influenced by free radical generation, aging, and the diseases. All the components of the respiratory system are affected by aging. Nutrition, smoking habits and sleep-related disorders also affect the respiratory system. Whether these changes are due to aging or associated with aging is a matter of debate. Since alterations caused by aging and cigarette smoke in lungs of various species were informed to be partly simulated with age-related alterations in human lung, the effects of oxidative agents and antioxidative parameters on both COPD and aging were evaluated. (C) 2002 Elsevier Science Ltd. All rights reserved.