OBJECTIVE: The authors reviewed basic science and clinical data on caffeine abuse, dependence, and withdrawal in order to make a conclusion about whether these disorders exist and should be included in DSM-IV and ICD-10. METHOD: Studies were located through computerized searches, reference sections of published articles, and written requests. RESULTS: The studies show that abstinence from caffeine induces a withdrawal syndrome of headache, fatigue, and drowsiness which begins within 12-24 hours and lasts about 1 week. The syndrome can be severe and appears to be one reason for continued use of coffee. The prevalence of this caffeine withdrawal syndrome is unknown. Use of caffeine may aggravate some common behavioral and medical disorders. In double-blind tests, a subset of coffee and soda drinkers reliably self- administered caffeinated beverages in preference to uncaffeinated beverages. Clinical indicators of dependence, such as difficulty stopping use of caffeine and use despite harm, have not been documented. CONCLUSIONS: Caffeine withdrawal but not caffeine abuse or dependence should be included as a diagnosis in DSM-IV and ICD-10. Future research should focus on whether some caffeine users exhibit clinical indicators of drug dependence.