Background: Breast cancer and genital cancer are known as cancers that affect people's relationships with their partners. Women with such cancers are emotionally vulnerable and need more support from their partners. The present systematic review and meta-analysis evaluated the effectiveness of couple-based interventions on the marital outcomes of patients with these cancers and their intimate partners. Methods: To perform this systematic review, Google Scholar and databases such as PubMed, Web of Science, Cochrane, Scopus, SID (Scientific Information Database), and Magiran were searched systematically. The reviewed studies included randomized controlled trials and quasiexperimental studies in which the intervention group, couple-based interventions, and the control group received routine care, general education or no intervention for cancer treatment. In this study, the included participants were patients with breast cancer or genital cancer and their intimate partners. The primary outcomes considered in this study included patients' marital adjustment, patients' marital satisfaction, patients' marital intimacy, and patients' marital relationships. The secondary outcomes were partners' marital adjustment, partners' marital satisfaction, partners' marital intimacy, and partners' marital relationships. A meta-analysis was performed with Review Manager v. 5.3 software (The Nordic Cochrane Centre, Cochrane Collaboration, 2014; Copenhagen, Denmark). The intervention impacts on continuous outcomes were measured using standardized mean differences (SMDs) with 95% confidence interval because of the use of various scales to evaluate the outcomes. The quality of evidence presented in the included studies was evaluated using the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach. In the subgroup analysis, the studied outcomes were divided into two parts (theory-based and non-theory-based) in terms of the theoretical context of couple-based interventions. Results: From a total of 138 retrieved studies, 14 trials were eligible for inclusion in the study. The results of the meta-analysis showed that the patient's marital satisfaction increased significantly with couple-based interventions (SMD 0.46, 95% confidence interval 0.07 to 0.85; 7 trials, 341 patients, very low certainty) compared to the control group, but the evidence was uncertain. However, there were no significant differences between the groups in the partner's marital satisfaction, the patient's and partner's marital adjustment, and the patient's and partner's marital intimacy. Additionally, the results of the subgroup analysis showed that the couple-based interventions significantly increased the patient's marital adjustment (SMD 1.96, 95% CI 0.87 to 3.06; 4 trials, 355 patients, very low certainty), the partner's marital adjustment (SMD 0.53, 95% CI 0.20 to 0.86; 4 trials, 347 partners, very low certainty), the patient's marital satisfaction (SMD 0.89, 95% CI 0.35 to 1.43; 2 trials, 123 patients, very low certainty), and the partner's marital satisfaction (SMD 0.57, 95% CI 0.20 to 0.94; 2 trials, 123 partners, very low certainty) compared to the control group in theory-based studies. In. However, in non-theory-based studies, the results of the meta-analysis revealed no significant differences between the intervention and control groups. Conclusions: The results of this study demonstrated the impact of couple-based interventions on the marital outcomes of patients with breast and genital cancers. Because of the very low confidence in the evidence, high-quality randomized trials with a sufficient sample size should be conducted considering the proper theoretical context. [ABSTRACT FROM AUTHOR]