The quantity and quality of protein ingested is determined by the dietary pattern. It has recently been suggested that the requirements for essential amino acids cannot be met on diets high in cereals unless at least 30% of the total protein intake is derived from animal sources. The sources of protein in the diet of adults who participated in the Diet and Nutritional Survey of British Adults (Gregoryet al., 1990) have been examined to explore whether there are groups of people eating high cereal protein diets. As the intake of cereals as a source of protein increases, the total intake of protein decreases. Relatively few people (21 out of 1844) derived more than 45% of their protein intake from cereals. Vegetarians (n= 29), identified as those not eating meat during the study, were much more likely to derive more than 45% of their total protein intake from cereals. Dietary patterns were explored in relation to age, gender, regional and social class differences. In the majority of the population, upper social class older women from the Central/South West parts of the UK were more likely to consume a higher cereal diet. Data published elsewhere from the present study population (Gregoryet al., 1990) show that this group is more likely to conform with current dietary guidelines for fat, fibre and vegetable consumption. If the suggestion about protein quality on cereal-based diets were true, this group of people, along with vegetarians, would be considered to be at increased risk. The results of the present analysis raise important questions about the extent to which our perceptions of the adequacy of diets in the short term are compatible with recommendations such as the current guidelines which have the objective of reducing the risk of chronic disease, such as coronary heart disease, in the longer term.