This paper presents an analysis of trends in mortality from malignant melanoma of the skin in The Netherlands, 1950-1988. Statistical analyses show that time period effects are needed to describe the mortality trends in The Netherlands. Because this contrasts with reports from other countries, in which the trends were ascribed to a cohort effect only, log-linear models including the three factors age, time period and birth cohort, were fitted to the data. To be able to separate time period effects from birth cohort effects we assumed a mathematical function for the mortality rates in relation to age. The results obtained in this way indicate that time period effects increased up to 1970. An increase of birth cohort effects is seen for cohorts born between 1900 and 1955. For cohorts born after 1955 the mortality from melanoma seems to decrease. The most plausible explanation for the time period effect probably is improvement in death certification.