Three systematic reviews with meta-analyses and two additional randomized controlled trials were identified regarding the clinical effectiveness of internet-delivered cognitive behavioural therapy for patients (16 years of age) with a primary diagnosis of post-traumatic stress disorder. The features of the treatment programs (e.g., number of modules, duration, level of guidance, and frequency of support), scales used to assess clinical outcomes, and characteristics of patients (e.g., age, sex, type of trauma) examined in these studies were heterogeneous. The evidence demonstrated that treatment with internet-delivered cognitive behavioural therapy resulted in improvement in severity of post-traumatic stress disorder symptoms compared to treatment with wait-list. There were generally no statistically significant differences between treatment with internet-delivered cognitive behavioural therapy and access to a psycho-educational website, internet-based supportive counselling, or optimized usual care for post-traumatic stress disorder symptom severity; however, these findings were based on one study per comparator. Additionally, one study reported no statistically significant differences between treatment with internet-delivered cognitive behavioural therapy that either included or did not include an exposure component for post-traumatic stress disorder symptom severity.Evidence examining how iCBT compared to face-to-face CBT, video-delivered CBT, or to alternative frequently used psychotherapy interventions was not identified in this review. The limitations of the included studies highlighted in this review, such as their open-label nature and lack of detailed reporting on potential confounders (e.g., comorbid psychological condition, patient use of medication) should be considered when interpreting these results.