The completeness of skin cancer registration in the Yorkshire region was evaluated for the year 1994 by the independent case ascertainment method. Patients diagnosed with skin cancer were identified from regional pathology laboratories, inpatient and outpatient hospital departments and general practices, and were matched against records held by the Northern and Yorkshire Cancer Registry and Information Services (NYCRIS). Out of 5987 skin cancer cases identified from 14 pathology laboratories, 123 general practices, 16 NHS Trusts inpatient databases and 7 dermatology outpatient departments, 83.5% had a matching record on the Cancer Register. The proportion of registered malignant melanoma (MM) and non-melanoma skin cancer (NMSC) cases were 87.5% (95% confidence interval (CI) 84.0–90.4) and 83.1% (95% CI 81.9–84.2) respectively. Skin cancers found in the pathology laboratories, the main notification sources of the registry, were under-ascertained by 15% (10% MM and 15% NMSC). Cases identified from general practices had a significantly lower proportion of matching registry records in comparison with other information sources. No record of histological confirmation could be found for 11% MM and 13% NMSC. Complete capture of pathology laboratory information, histological confirmation of all lesions suspected of skin cancer and routine receipt of hospital patient administration system information supplementary to that from pathology laboratories are measures that would provide the most substantial improvement to ascertainment of skin cancer data.