Patients with rhonchopathy, which includes obstructive sleep apnea syndrome (OSAS), who report sleepy spells at the wheel do poorly on simulated monotonous driving tests and have a twofold to threefold increase in traffic accidents. To assess whether drivers with rhonchopathy (heavy snoring, sleep disturbances, and daytime sleepiness) cause fewer automobile accidents after uvulopalatopharyngoplasty (UPPP), the car accident rate for the first 5 years after surgery was compared to the rate of the 5 years immediately before the operation. Data were collected by means of a self-report questionnaire. Fifty-six patients with rhonchopathy were compared to 142 controls without rhonchopathy who had been subjected to nasal surgery. The response rates were 96% and 94%, respectively. The reported habitual sleepiness while driving had disappeared in 87% (P < .001) of drivers who had the problem preoperatively. The accident risk reduction (corrected for mileage) in patients was almost four times greater than the reduction in controls (P < .001) after surgery. The relative rate of patients involved in any single-car accident fell by 77% (P < .05), and the relative rate of single-car accidents fell by 83% (P < .001). It is concluded that drivers with rhonchopathy have an increased risk for car accidents, especially single-car accidents, but that this risk returns to normal after UPPP.