Abstrak. Tujuan penelitian ini adalah untuk mengetahui adakah pengaruh media 3D Anatomy and Physiology berbasis Lesson Study terhadap hasil belajar dan kemampuan berpikir kritis siswa. Metode penelitian yang digunakan adalah metode pre-experimental dengan sampel menggunakan 35 siswa yang dipilih menggunakan teknik purposive sampling dan desain penelitian one grup pretest-posttest. Berdasarkan hasil penelitian, pengaruh media 3D Anatomy and Physiology sebagai media pembelajaran dan kegiatan Lesson Study sebagai bentuk upaya meningkatkan kualitas pembelajaran pada materi sistem sirkulasi, didapatkan bahwa uji hipotesis data hasil belajar dengan Wilcoxon Match Pairs Test memperoleh nilai signifikansi 0,000 (< 0,05) dan uji hipotesis kemampuan berpikir kritis dengan uji t memperoleh nilai 0,000 (< 0,05). Hal tersebut, dapat diartikan ada pengaruh media 3D Anatomy and Physiology berbasis Lesson Study terhadap hasil belajar dan kemampuan berpikir kritis siswa. Kegiatan Lesson Study yang dilakukan dalam penelitian, terdiri dari tahap Plan (perencanaan), Do (pelaksanaan), dan See (refleksi) selama 3 kali pertemuan pembelajaran materi sistem sirkulasi. Pengaruh yang ditunjukkan setiap indikator hasil belajar dan kemampuan berpikir kritis siswa, menunjukkan bahwa peningkatan tertinggi indikator hasil belajar terdapat pada indikator C4 (menganalisis) dan setelahnya pada indikator C1 (mengingat), sedangkan peningkatan terendah terdapat pada indikator C2 (memahami). Selanjtutnya, peningkatan nilai tertinggi indikator kemampuan berpikir kritis siswa terdapat pada indikator dukungan dasar (basic support), sedangkan peningkatan terendah terdapat pada indikator strategi dan taktik (strategy and tactics). Asbtract. The purpose of this study was to determine whether there is an influence of 3D Anatomy and Physiology media based on Lesson Study on student learning outcomes and critical thinking skills. The research method used was a pre-experimental method with a sample using 35 students selected using purposive sampling techniques and one group pretest-posttest research design. Based on the results of the study, the influence of 3D Anatomy and Physiology media as a learning medium and Lesson Study activities as an effort to improve the quality of learning on circulatory system material, it was found that the hypothesis test of learning outcome data with the Wilcoxon Match Pairs Test obtained a significance value of 0.000 (< 0.05) and a hypothesis test of critical thinking skills with a t test obtained a value of 0.000 (< 0.05). This can be interpreted as the influence of 3D Anatomy and Physiology media based on Lesson Study on student learning outcomes and critical thinking skills. Lesson Study activities carried out in research consist of Plan (planning), Do (implementation), and See (reflection) stages for 3 learning meetings of circulation system material. The influence shown by each indicator of learning outcomes and students' critical thinking skills, shows that the highest increase in learning outcome indicators is found in indicator C4 (analyzing) and afterwards in indicator C1 (remembering), while the lowest increase is found in indicator C2 (understanding). Furthermore, the highest increase in the indicator of students' critical thinking ability was found in (the basic support) indicator, while the lowest increase was found in (the strategy and tactics) indicator.