IntroductionPersistent pain (PP) and long-term conditions are all associated with psychological well-being. Less is known about their associations with reduced psychological well-being when co-occurring. We investigated how PP and long-term physical and mental conditions relate to psychological well-being when occurring together.MethodData collected in the Danish population-based Lolland-Falster Health study were used in this cross-sectional study. Participants aged ≥18 years completing questions concerning PP, long-term conditions and psychological well-being were included. PP and long-term conditions were defined as conditions lasting 6 months or longer. Psychological well-being was assessed by the World Health Organization Well-Being Index (WHO-5). Multiple linear regression investigated combinations of PP and physical and mental long-term conditions and their associations with WHO-5.ResultsOf 11,711 participants, 10,744 had available data. One third had PP (n = 3250), while 6144 (57%), 213 (2%) and 946 (9%) reported having only physical conditions, only mental conditions or both, respectively. All combinations of PP and long-term conditions were negatively associated with WHO-5. PP in combination with mental (?23.1 (95% CI ?28.3 to ?17.8)) or both physical and mental conditions (?25.1 (?26.7 to ?23.52) yielded the strongest negative associations. Two or more pain sites together with long-term physical and mental conditions was associated with a lower WHO-5 score (?6.2 (?8.9 to ?3.5) compared to none or one pain site.ConclusionThe presence of PP and long-term conditions, in particular mental conditions, were strongly associated with worse psychological well-being. This highlights the importance of assessing psychological well-being in individuals with PP and long-term conditions.