OBJECTIVES: To validate a symptom assessment instrument for patients with acute bacterial sinusitis(ABS). METHODS: Data were obtained from a randomized, double-blind, equivalency study of adults with radiographic evidence of ABS treated with telithromycin 800 mg od for 5 days (n=159) or moxifloxacin 400 mg od for 10 days (n=163). A 5-item Acute Sinusitis Daily Symptom Survey (ASDSS) was developed for use in the trial. The five items of the ADSS (nasal congestion, runny nose, postnasal discharge, thick nasal discharge, and facial pain/pressure) used a six-point adjectival scale ranging from zero (“no problem”) to five (“problem as bad as it can be”). Overall ASDSS score was the sum of item responses. Subjects completed the ASDSS daily for the first 17 days of the study. At Visits 1 (Day 1)2 (Day 3-5), and 4 (Day 17-24), subjects were assessed for quality of life (SF-36, acute form), treatment outcomes (success/failure), and infection-related signs/symptoms. Data were pooled across treatment groups. RESULTS: Survey completion rates ranged from 100% (Day 3) to 79.8% (Day 17). Pearson correlations between the ASDSS items ranged from 0.258 to 0.639. Test-retest intraclass correlation coefficients (ICC) measured over a 5 day interval (Day 1-5) were: nasal congestion (0.681), runny nose (0.612), postnasal discharge (0.689), thick nasal discharge (0.669), and facial pain/pressure (0.679). Cronbach’s alpha was 0.788 and test-retest reliability (ICC) of the total score was 0.694. Pearson correlations between ASDSS and the SF-36 scales at Visit 4 ranged from -0.293 (mental health) to -0.496 (vitality). Pearson correlations with the ASDSS at Visit four were 0.599 for major and 0.634 for minor symptoms of infection. Mean ASDSS scores at Visit four were 3.34 for subjects deemed treatment successes and 10.35 for treatment failures (F=2.60, p<0.0001). CONCLUSIONS: The ASDSS appears to be a valid symptom assessment instrument for patients with ABS.