In a previous study conducted by mail questionnaire and with a large proportion of surrogate responders, we found differences in smoking habits, age at diagnosis, tumour cell type distribution and occupational exposures between men and women who developed primary lung cancer. This study was designed to confirm those findings by conducting personal case interviews and extend them by examining the impact of certain biological factors. We have investigated demographic, smoking, occupational and medical history sex differences in cases with primary lung cancer by interviewing 273 male and 103 female cases diagnosed between November 1983 and July 1986. The females were significantly younger at diagnosis, a pattern consistent for all cell types. Squamous cell (40%), small cell anaplastic (20%) and adenocarcinomas (16%) were the most prevalent cell types in men. In women, similar frequencies of adenocarcinomas (32%) and squamous cell carcinomas (29%) occurred. Despite a higher prevalence of physician diagnosed allergy and asthma among women, minimal sex differences in the prevalence of atopy as measured by prick skin test were found. Female cases were more likely to be lifetime non-smokers (15% vs 3%), to have started smoking on average 3 years older and to smoke 6 fewer cigarettes per day. The mean pack years of female cases was significantly lower than males' for squamous, adenocarcinoma and small cell anaplastic tumours. The majority of these women had not been occupationally exposed to any substance known to be carcinogenic or to damage the lung. However, in a small subset of cases pulmonary function variables were as depressed in women as in men with significantly higher mean pack years.(ABSTRACT TRUNCATED AT 250 WORDS)