Objective: To study the psychometric properties and preference for five different pain intensity scales (horizontal visual analog scale [VAS], vertical VAS, Box-11, Box-21, and verbal descriptor scale) across different age groups. Design: Chronic pain patients rated their present, average, weakest, and strongest pain on five different scales, and indicated scale preference. Setting: Outpatient pain facility. Results: The number of mistakes on all scales increased with increasing age, and the VAS appeared to be most prone to making mistakes. All scales appeared to be sufficiently valid, but the verbal descriptor scale was less related to the common underlying pain factor than the other scales. The Box-21 was the most preferred scale overall, although patients aged > 75 years especially preferred the verbal descriptor scale. Conclusion: The numerical Box-21 scale is an excellent choice for pain intensity assessment in heterogeneous patient groups. The verbal descriptor scales may be considered when the study population consists of a majority of older persons.