There is mounting evidence suggesting that by increasing the frequency of treatment sessions, posttraumatic stress disorder (PTSD) treatment outcomes significantly improve. As part of an ongoing research project, this study examined the safety and effectiveness of intensive eye movement desensitization and reprocessing (EMDR) therapy in a group of seven (four female) patients suffering from complex PTSD and multiple comorbidities resulting from childhood sexual abuse, physical abuse, and/or work and combat-related trauma. Treatment was not preceded by a preparation phase and consisted of 2 × 4 consecutive days of EMDR therapy administered in morning and afternoon sessions of 90 minutes each, interspersed with intensive physical activity and psychoeducation. Outcome measures were the Clinician-Administered PTSD Scale (CAPS) and the PTSD Symptom Scale Self-report questionnaire (PSS-SR). During treatment, neither personal adverse events nor dropout occurred. CAPS scores decreased significantly from pre- to posttreatment, and four of the seven patients lost their PTSD diagnosis as established with the CAPS. The results were maintained at 3-month follow-up. Effect sizes (Cohen’s d) on the CAPS and PSS-SR were large: 3.2, 1.7 (prepost) and 2.3, 2.1 (prefollow-up), respectively. The results of this case series suggest that an intensive program using EMDR therapy is a potentially safe and effective treatment alternative for complex PTSD. The application of massed, consecutive days of treatments using EMDR therapy for patients suffering from PTSD, particularly those with multiple comorbidities, merits more clinical and research attention.