ABSTRACT Background/objectives Little is known about time trends in diet quality and associated inequalities in the United Kingdom (UK). This study aimed to examine trends in adherence to four UK dietary recommendations, overall, and among sociodemographic subgroups, from 1986 to 2012. Subjects/methods We conducted a repeated cross-sectional analysis using data from three UK diet surveys: Dietary and Nutritional Survey of British Adults 1986-87 (n=2018), National Diet and Nutrition Survey (NDNS) 2000-01 (n=1683), and NDNS Rolling Programme 2008-12 (n=1632). We measured adherence to dietary recommendations for fruit and vegetables, salt, oily fish, and red and processed meat, estimated using food diary record data. We compared adherence across surveys and by four sociodemographic characteristics: sex, age, socioeconomic position, and ethnicity. Results Overall, population adherence to dietary recommendations was low to moderate, but improved over time. There were inequalities in adherence to all recommendations at all timepoints according to one or more sociodemographic characteristic. When inequalities were present, women, older adults, those with non-manual occupations, and non-whites were more likely to adhere to dietary recommendations. Whilst some dietary inequalities declined, most persisted across the three surveys. Conclusions The persistence of most inequalities highlights the need for further interventions to reduce dietary inequalities, as well as improve overall population diet. The greatest simultaneous improvement in population adherence and reduction of inequalities was observed for salt, which may reflect the success of the UK Salt Reduction Programme. Similarly comprehensive programmes should be encouraged for other dietary components.