Self-rated health (SRH) accounts comprehensively for many health domains. The aim of this paper was to investigate time trends and associations between age-comparative self-rated health and some known determinants in a general population aged 24–34 years. Population-based cross-sectional surveys were performed in 1990, 1994, 1999, 2004, 2009 and 2014 in Northern Sweden. Out of 3500 invited persons, 1811 responded. Comparative SRH was measured on a three-grade ordinal scale by the question: “How would you assess your general health condition compared to persons of your own age?” with the alternatives “better/worse/similar”. Over the period 1990 to 2014, the percentage of women rating comparative SRH as “worse” increased steadily, from 8.5% in 1990 reaching 20% in 2014 (p for trend 0.007). Among men, this pattern was almost the opposite, with increasing proportions rating “better” (p for trend <0.000). Time trends for physical activity in leisure time; length of education; Body Mass Index; anxiety; depressive emotions and satisfaction with economy showed a similar pattern for men and women. Factors that might contribute to the development of time trends for comparative SRH are discussed.