This posthearing brief contained a summary of the results of the largest study to date of 353,180 female and 126,500 male never smokers enrolled in 1982 in the American Cancer Society's Cancer Prevention Study-II. Ten percent of married men, and 28% of married women were married to currently smoking spouses. There was a 22% higher coronary heart disease (CHD) mortality among never smoking men married to currently smoking women compared to those married to wives who had never smoked, after controlling for cardiovascular risk factors. Never smokers living with former smokers showed no increased risk. However, a different analysis of the data indicated that there was no increased CHD risk for those exposed to environmental tobacco smoke (ETS) from a spouse. Data from an additional study of heart disease connected to lung cancer and spousal smoking was also reviewed, and the selection criteria were called into question. The selection strategy for controls resulted in controls who were less likely than cases to die of any chronic diseases. Also of concern was the quality of data available on decedent's smoking status and on ETS exposure in this study. NIOSH recommends that little weight or no weight at all be given to analyses of spousal smoking and ETS exposure based on this study.