AbstrakPembangunan saluran transmisi listrik tegangan tinggi diduga dapat merugikan manusia atau makhluk hidup lain. Tujuan penelitian untuk mengetahui pengaruh paparan medan listrik tegangan tinggi pada ketebalan miokardium ventrikel kiri mencit jantan (Mus musculus L.). Penelitian dilaksanakan di Laboratorium Zoologi Fakultas Matematika dan Ilmu Pengetahuan Alam Universitas Lampung serta Laboratorium Patologi Balai Penyidikan dan Pengujian Veteriner Regional III Bandar Lampung, pada bulan Juni−November 2011.Penelitian menggunakan rancangan acak lengkap dengan 4 perlakuan, ulangan 6 kali, dan dibagi dalam empat kelompok. Kelompok kontrol (K) tidak diberi perlakuan, kelompok 1 (P1) diberi paparan 5 kV/m, kelompok 2 (P2) diberi paparan 6 kV/m, dan kelompok 3 (P3) diberi paparan 7 kV/m, masing-masing 8 jam/hari selama 37 hari. Data dianalisis menggunakan analysis of variance. Hasil penelitian didapatkan ketebalan miokardium ventrikel kiri mencit jantan pada K sebesar 1.329,83±173,29 µm; P1 sebesar 1.507,50±109,24 µm; P2 sebesar 1.536,70±103.42 µm; dan P3 sebesar 1.574.23±123,36 µm. Terdapat peningkatan ketebalan miokardium rata-rata dengan bertambahnya daya paparan medan listrik (p=0,019). Simpulan, terdapat hubungan antara paparan medan listrik tegangan tinggi dan perubahan ukuran ketebalan miokardium ventrikel kiri mencit jantan, semakin tinggi paparan medan listrik semakin tebal miokardium ventrikel kiri mencit jantan. Research using completely randomized design with 4 treatments, replicated 6 times and divided into four groups.The control group (K) was not given treatment, group 1 (P1) given exposure to 5 kV/m, group 2 (P2) given exposure to 6 kV/ mand group 3 (P3) given exposure to 7 kV/m for 8 hours/day, to 37 days. Data were analyzed using analysis of variance. The results obtained thickness of the left ventricular myocardium of male mice at K1,329.83±173.29 μm; P1 at 1,507.50±109.24 μm; P2 at 1,536.70±103.42 μm, and P3 at 1,574.23±123.36 μm. There was an increase in the average thickness of the myocardium with increasing exposure to power an electric field with a statistical test obtained (p=0.019). In conclusion, there is a significant relationship between exposure to high-voltage electric field to change the size of the thickness of the left ventricular myocardium male mice, the higher the electric field exposure thicker left ventricular myocardium male mice. [MKB. 2013;45(3):155-60]