We aimed to describe the incidence of new episodes of molluscum contagiosum, scabies and lichen planus presenting to general practitioners in England and Wales. We examined data collected in a sentinel practice network (the Weekly Returns Service of the Royal College of General Practitioners) in which about half a million persons were observed each year over the period 1994-2003. The incidence of molluscum contagiosum in males was 243/100,000 person-years and in females 231; of scabies, males 351, females 437; of lichen planus, males 32, females 37. Incidence varied by year and age. Ninety per cent of molluscum contagiosum episodes were reported in children aged 0-14 years, where incidence in 2000 (midpoint of a 6-year period of stable incidence) was 1265/100,000 (95% CI 1240-1290). Scabies affected all ages and annual incidence ranged between 233 (95% CI 220-246) in 2003 and 470 (95% CI 452-488) in 2000. Lichen planus occurred chiefly in persons aged over 45 years: incidence (all ages) ranged between 27 (95% CI 23-31) in 2003 and 43 (95% CI 37-49) in 1998. The relative risk of female to male incidence (all ages) of molluscum contagiosum was 0.95 (95% CI 0.91-0.99); of scabies 1.25 (95% CI 1.21-1.28); and of lichen planus 1.19 (95% CI 1.08-1.13).