OBJECTIVE: To compare Adverse Drug Events (ADE) associated with Selective Serotonin Re-uptake Inhibitors (SSRI) in two Managed Care Organizations (MCO). METHODS: Medical records for two MCOs in central Texas were reviewed. Scott and White Health Plan (SWHP) is a general health plan and Alamo Mental Health Group (AMHG) is a behavioral/mental health organization. Inclusion criteria for both settings were patients over 18 years old that had a diagnosis of depression and had a new prescription for an SSRI. RESULTS: A total of 337 patients in SWHP and 361 patients in AMHG met the inclusion criteria. About 40% (N=135) of SWHP patients and 40% (N=144) of AMHG patients had at least one adverse drug event (ADE) associated with an SSRI noted in their medical record. The most common ADEs reported were sleep cycle disturbances, e.g. insomnia, daytime sedation - 13%; GI disturbances, e.g. diarrhea, nausea/vomiting - 11%; sexual dysfunction - 7%; and anxiety/nervousness - 5%. Of those with reported ADEs (N=135 + 144=279), at least one therapy change due to ADEs was made for 71% (N=96) of the SWHP patients and 69% (N=100) of the AMHG patients: 25% were switched to another antidepressant; 20% had a medication added; 19% had a change in the dose/regimen of their index medication; 12% discontinued their index medication. The most common medication added to treat side effects at SWHP was trazodone, while the most common addition at AMHG was bupropion. CONCLUSIONS: Although the health-care settings differed in type (general versus behavioral/mental health), results were strikingly similar. About 40% of the patients reported ADEs and of these, about 70% had at least one change made to their therapy, many discontinuing the original medication. Strategies for treating ADEs appeared to vary by setting, which may have cost implications. Future research might examine the impact of ADE strategies and patient education on continuity of treatment.