To examine the hypothesis that the tendency to raised blood pressure in snorers is associated with nocturnal hypoxaemia and snoring, blood pressure was measured and snoring, oxyhaemoglobin saturation (SaO2), and thoraco-abdominal movements were monitored overnight in 372 snorers. Snoring was quantified as number of snores per hour of sleep (snoring index). The data were analysed by multiple linear regression of diastolic blood pressure against age, body mass index (BMI), apnoea-hypopnoea index (AHI, number of episodes per hour), snoring index, and SaO2. Diastolic blood pressure correlated significantly with BMI, AHI, and mean nocturnal oxygen saturation, but not with the snoring index. However, snoring index correlated with BMI, AHI, and mean nocturnal oxygen saturation. Snoring is thus not a direct risk factor for hypertension, but may influence blood pressure via its association with obesity, obstructive sleep apnoea, and nocturnal hypoxaemia.