In a randomized controlled trial of sharing medical records with ambulatory adults as part of periodic health examinations, 193 patients (experimental group; 37 smokers) received copies of their medical records while 208 patients (control group; 50 smokers) did not. Awareness of smoking as a health problem and smoking behavior were assessed two weeks and six months later. At two weeks, 46% of experimental group smokers indicated that smoking was a major health problem, compared with 21% of the control group (p less than 0.02), and 43% of the experimental group had quit or reduced smoking, compared with 20% of the control group (p less than 0.02). At six months smoking problem awareness was not significantly different (33% experimental group vs. 14% control group, p = NS), but 65% of the experimental group had quit or reduced compared with 29% of the control group (p less than 0.04). Sharing medical records with smokers after periodic health examinations is effective in enhancing patient awareness of smoking as a health problem and beginning the process of changing smoking behavior.