The smoking habits of 184 attendees (mean age 47 years, 101 men) at a hospital-based lipid clinic were reviewed in conjunction with a measurement of serum thiocyanate level which is a marker for smoking over the previous two weeks. Advice against smoking is routinely given at the clinic. We found 84 (46%) patients to remain active smokers of whom 78 admitted to smoking and 6 were identified on the basis of a serum thiocyanate level greater than 100 micromol/l. Smoking was more prevalent amongst women than men (52% v 33%). We have identified a high proportion of patients attending an outpatient lipid clinic as remaining active smokers despite receiving advice against cigarette smoking. This emphasises the need for more effective counselling against smoking in a multiple risk factor intervention approach to ischaemic heart disease.