Among common fragile sites, fra(3)(p14.2) is the most expressed either spontaneously or after treatment with aphidicolin (APC) in lymphocyte cultures. Because recurrent chromosomal abnormalities involving the short arm of chromosome 3 in tumor tissue are present in various malignancies, including lung cancer, the induction of fra(3)(p14.2) elicited by APC was investigated with the aim of detecting possible interindividual polymorphism in its expression that might be relevant to predisposition toward cancer-related events. Thirty-four patients affected with various lung cancers (14 squamous cell carcinomas, 13 adenocarcinomas, and seven small cell carcinomas) and 14 controls (patients undergoing routine routine follow-up after coronary by-pass) were included in this study. The frequency of fra(3)(p14.2) expression was not significantly different among the patients grouped either by disease or by sex and age. It was estimated that fra(3)(p14.2) accounts for about 20% of total breakage in APC-treated lymphocyte cultures from the general population.