The epidemiologic studies of pilot-related factors in aircraft crashes are reviewed with regard to: 1) study design and methods; 2) major findings; and 3) data and methodological issues. In the last 60 years, numerous studies have been conducted to examine the relationships of pilot characteristics to the risk of aircraft crashes. Much attention has been paid to pilots' medical condition, age, flight experience, and alcohol use. Most studies were based on crash analysis, using case reports and case series. Few studies have applied a formal, rigorous epidemiologic design. Planned case-control and cohort studies are extremely rare. In some cases, the deficiencies in study design and data analysis have resulted in controversial findings. More epidemiologic studies using state-of-the-art methodology are needed to identify various risk factors of aircraft crashes, to better understand the interrelationships among pilot, aircraft, and environment, and to develop and assess safety policies and other intervention programs.