Abstract Rapid-access clinics are designed to improve the early detection and prognosis of melanoma, but there is little hard evidence in the literature of their effectiveness. We established a pigmented lesion clinic (PLC) in 2002 and have previously demonstrated a subsequent reduction in melanoma thickness at our hospital. We undertook a retrospective cohort study to assess the long-term effects. Data for all melanomas diagnosed in the Republic of Ireland between 1 January 1998 and 31 December 2019 were provided by the National Cancer Registry Ireland (n = 15 619). We excluded T0 and Tis and unknown T melanomas. Our PLC was found to have a higher proportion of tumours diagnosed at an earlier stage of T1 (51.6%) vs. the region/county where the PLC is based (37.8%) and Ireland (40.3%). Following the introduction of the PLC, from 2003 to 2007, a significant difference was noted between our PLC and the rest of Ireland, with a higher proportion of T1 tumours diagnosed (41.6% vs. 29.7%; P < 0.001). For the region, the percentage of T1 tumours was lower than for the rest of the country, but this difference fell short of significance (34.5%; P = 0.057). In the two 5-year periods following this (2008–2013 and 2014–2019), our PLC had significantly more early tumours (44.4% and 62.1%, respectively) than the rest of Ireland (35.9% and 52.2%, respectively; P < 0.001 for both time periods). More PLCs have been established across the country, probably accounting for the higher proportion of early-stage melanomas diagnosed in 2014–2019. The figures for the region were also significantly better than those for the rest of the country [40.7% and 55.7% (P = 0.008 and P = 0.039), respectively], suggesting that the PLC has had an effect on prognosis, resulting in a greater proportion of early melanomas in the region vs. Ireland. Preliminary analysis found a hazard ratio (HR) of 0.78, or a 22% reduced risk death, at 5 years (unadjusted Cox proportional hazard regression on all nonmetastatic melanoma with known T diagnosed 1998–2019, n = 16,489) for those attending the PLC vs. the rest of Ireland. Patients in the rest of the region were found to have a higher HR (1.15) vs. the rest of Ireland. The PLC appears to have contributed to improved prognosis in the region in the years following its establishment. This study supports the long-term benefits of a PLC over the course of more than 20 years.