The incidence of cutaneous malignant melanoma (CMM) is steadily increasing. Most of the patients have thin CMM with a good prognosis and a 5-year survival of about 90%. The prognosis is highly related to tumour thickness and clinical stage at diagnosis. Effective systemic treatment for patients with metastatic disease has only recently been available. This thesis aims to increase knowledge of trends in tumour thickness, prognostic factors, socioeconomic differences and medical costs in patients with CMM. The population-based Swedish melanoma register is the main source of data in all papers in the thesis. Papers I-III include patients from all of Sweden while paper IV is delimited to the County of Östergötland. Cox regression and logistic regression are the main multivariable methods used. Paper IV is focused on stage-specific costs of CMM by comparing direct healthcare costs to a general population. For men, there has been a shift over time towards thinner tumours at diagnosis accompanied by an improved survival. Women are still diagnosed with considerably thinner tumours and they experience a better survival than men. Tumour ulceration, tumour thickness and Clark’s level of invasion all showed significant independent long-term prognostic information in T1 CMMs. By combining these factors, three distinct prognostic subgroups were identified. Lower level of education was associated with reduced CMM-specific survival, which may at least partially be attributed to a more advanced stage at diagnosis. The direct healthcare costs for CMM patients were significantly higher than for the general population, independent of clinical stage. CMM patients diagnosed in clinical stage III-IV were associated with particularly high costs. Even though the survival among Swedish patients with CMM is among the highest in the world and still seems to improve, the results of this thesis emphasise the need of improved early detection strategies. This may be of particular concern in men, older women, and groups with a low level of education. The results also imply that the costs for the management of CMM patients may be reduced if early detection efforts are successful and lead to a more favourable stage distribution. The finding of a better risk stratification of thin CMMs may help to improve the management of this large patient group.