Premature corneal arcus may identify individuals with hyperlipidaemia and increased cardiovascular risk. We have attempted to quantitate relationships through determination of graded prevalence of corneal arcus with age for 81 males and 73 females suffering from heterozygous familial hypercholesterolaemia (HFH) at presentation, and for 280 male and 353 female unselected patients (age range 16–76 years) attending a country general practice. Some degree of arcus affected 50% of HFH patients by age 31–35 years, and 50% of practice patients by age 41–45 years. Complete full ring arcus affected 50% of the familial hypercholesterolaemia (FH) group by age 50 years, with only 5% similarly affected in the non-FH group. Arcus grade with age was advanced by some 5 years in males versus females. Premature arcus potentially alerting to HFH can be broadly defined for males and females combined, as heavy full ring by age 50 years, or any degree of arcus by age 30–35 years. Arcus grade was not related to the presence of coronary disease. Accelerated development of corneal arcus with age is an indicator of HFH, but premature arcus is not an additional marker of premature coronary disease for individual cases of HFH.