OBJECTIVES: Clinical studies of dry eye disease (DED), a highly symptomatic disease, often ask patients to evaluate their DED symptoms using patient-reported outcomes instruments. Most of these instruments use a one-week recall period. The effect of this recall period on the accuracy of DED symptom assessments has not been documented. The purpose of our research was to compare self‑reported DED symptoms between one-week and daily recall periods. METHODS: We enrolled 156 DED patients to a web-based observational study to assess their DED symptoms once a day for 9 days. For each of the 14 symptoms, we asked the patients to rate the frequency and intensity on a 0-6 rating scale, with a higher score indicating worse symptom. The assessments on Days 1 and 9 had a one-week recall period, while the assessments on Days 2-8 had a one-day recall period. We then calculated the mean weekly scores for Day 1 and Day 9 and the mean daily scores for Days 2-8, and tested the differences between the mean weekly and daily scores using matched-pair t tests without multiplicity adjustment. RESULTS: The Day 1 mean weekly scores were significantly higher than the mean daily scores for all 14 symptoms in both frequency and intensity. The Day 1 mean weekly scores were also significantly higher than the Day 9 mean weekly scores in 10 frequency and 11 intensity scores. The Day 9 mean weekly scores were slightly higher than the daily scores; however, most of the differences were not statistically significant. CONCLUSIONS: Patients’ self-ratings of their DED symptoms using a one-week recall period are consistently inflated when compared to their ratings using a one-day recall period. Such inflation should be considered when designing clinical studies for DED.