Postoperative pain after functional endoscopic sinus surgery (FESS) and its optimal management has not been described in detail. The objective was to evaluate pain, its influencing factors and its management on the first postoperative day following FESS. In a prospective case study, 101 FESS patients were examined after removal of the nasal packing within the Quality Improvement in Postoperative Pain Management (QUIPS) project allowing a standardized assessment of patients' characteristics, pain parameters, outcome and process parameters. The influence of these parameters on the patients' postoperative pain was estimated by univariate and multivariate statistic analysis. Pain during the first postoperative day after FESS was moderate. Younger patients reported significantly more pain than did older patients. Specific counseling about the possibilities of postoperative pain management reduced pain intensity highly significantly in univariate and multivariate analysis. Patients demanding for pain relief in the recovery room and on the ward predominantly received acetaminophen as non-opioid and piritramide as opioid. This pain management was obviously insufficient as these patients still reported significantly more from pain on the first postoperative day than patients not demanding for pain relief. We conclude that QUIPS could help to optimize the quality of postoperative pain management following FESS.