Pendahuluan: Secara nasional di Indonesia, presentase pemberian ASI eksklusif pada bayi usia 0-5 bulan terus mengalami peningkatan dari tahun ke tahun. Tahun 2023 presentase pemberian ASI eksklusif sebesar 73,93% meningkat dibandingkan tahun 2022 hanya 71,58%. Keberhasilan menyusui tak luput dari peran ayah. Namun, keterlibatan ayah masih dirasa kurang, ayah mengalami kebingungan menghadapi masalah menyusui sejak masih berada diruang perawatan post partum. Penting bagi tenaga kesehatan dapat melibatkan ayah dalam pemberian ASI melalui edukasi kesehatan, konseling, penerapan peer group ayah. Tujuan: mengetahui pengaruh intervensi peer group ayah terhadap peningkatan peran ayah mendukung ibu menyusui eksklusif.  Metode : desain quasy experiment dengan pre dan post test with control group. Hasil: Ada perbedaan tingkat pengetahuan, sikap dan peran ayah setelah diberikan edukasi dan peer group ayah lebih baik dibandingkan kelompok yang hanya diberikan edukasi saja dengan analisa uji Wilcoxon dengan p-value 0,000. Rekomendasi: Pihak pelayanan kesehatan perlu mempertimbangkan untuk melibatkan ayah dengan menerapkan peer group ayah dalam memberikan edukasi laktasi.

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Introduction: Nationally in Indonesia, the percentage of exclusive breastfeeding for babies aged 0-5 months continues to increase from year to year. In 2023, the percentage of exclusive breastfeeding will be 73.93%, an increase compared to 2022, which is only 71.58%. The success of breastfeeding cannot be separated from the role of the father. However, the father's involvement was still felt to be lacking, the father experienced confusion regarding breastfeeding problems since he was still in the post partum care room. It is important for health workers to involve fathers in breastfeeding through health education, counseling, implementation of fathers' peer groups. Objective: to determine the effect of father's peer group intervention on increasing father's role in supporting exclusive breastfeeding mothers. Method: quasi-experiment design with pre and post test with control group. Results: There are differences in the level of knowledge, attitudes and roles of fathers after being given a peer group, which is better than fathers who received education according to hospital standards with Wilcoxon test analysis with a p-value of 0.000. Recommendation: Health services need to consider involving fathers by implementing fathers' peer groups in providing lactation education.