Low protein intake may accelerate age-related loss of lean mass and physical function. We investigated prevalence of low protein intake (<1.0 g/kg/day) and the associations between dietary patterns, key modifiable risk factors and low protein intake in self-reliant community-dwelling adults ≥ 80 years. This cross-sectional study consisted of two home-visits. Data collection consisted of physical measurements (physical function, weight, height, physical activity) and self-report of nutritional intake (4-day food records), appetite, eating symptoms, dysphagia, dental status, medical conditions, pain and living status. Binary analyses were performed to compare participants with low and normal protein intake. Multiple logistic regression analyses were performed to investigate associations between low protein intake, dietary patterns and modifiable risk factors adjusted for age, sex, BMI-categories and diseases. N=126 were included in the study from January 2017 to August 2018. Prevalence of low protein intake was 54%. A greater day-to-day variation in protein intake was associated with low protein intake (adjusted OR 2.5 CI: 1.14-5.48). Participants with low protein intake had a higher prevalence of nausea, diarrhoea and mouth dryness. Reduced appetite, mouth dryness and pain increased odds of low protein intake (adjusted OR 3.06 CI: 1.23-7.63, OR 3.41 CI:1.51-7.7, OR 1.54 CI:1.00-2.36, respectively). There was a high prevalence of low protein intake in community-dwelling adults ≥ 80-years. Day-to-day variability, reduced appetite, mouth dryness and pain may be potentially modifiable risk factors. Targeting dietary patterns and risk factors in primary prevention strategies may be important to improve intake of protein and minimise risk of physical frailty.