The intensity of pain cannot be measured directly but can only be described subjectively. This obviously complicates the assessment especially in the younger age group. Pain evaluation and documentation are essential for good results in pain therapy. Pain can be measured by pain scales which should fulfill the requirements of practicability, reliability and validity. In neonates and children up to 4 years of age, standardized scales have been developed for observation of their activities. Children in the age group 4-6 years old are able to communicate about pain. At this age self-report scales can be used to assess pain sensations."Quality Improvement in Postoperative Pain Management in Infants" (QUIPSInfant) represents a new tool for pediatric outcome evaluation, consisting of standardized data acquisition of outcome and process quality indicators.