Pendahuluan: Early childhood caries (ECC) sering terjadi pada anak di Indonesia. Lesi karies pada permukaan gigi sulung yang terjadi pada anak usia 2 sampai 3 tahun disebut ECC karena mengonsumsi makanan dan minuman kariogenik. Tujuan penelitian mengetahui ECC pada balita usia 2-5 tahun yang mengonsumsi air susu ibu (ASI) dan susu formula. Metode: Jenis penelitian observasional deskriptif cross-sectional. Populasi penelitian sebanyak 50 balita usia 2-5 tahun. Teknik pengambilan sampel total sampling. Pengambilan data menggunakan kuesioner dan wawancara. Data dianalisis menggunakan software Microsoft Excel®. Hasil: ECC dialami balita 2-5 tahun sebanyak 58% dari total reponden. ECC pada usia 2-3 tahun lebih banyak dialami oleh laki laki dan sebaliknya pada usia 4-5 tahun. Balita usia 2-5 tahun sebanyak 34% mengonsumsi susu formula. Lamanya balita mengonsumsi ASI 0-2 tahun sebanyak 84,8% dan susu formula sebanyak 82,4%. Frekuensi mengonsumsi ASI 7-8 kali sehari sebanyak 73% dan konsumsi susu formula 3-4 kali sehari sebanyak 35,3%. Waktu balita mengonsumsi ASI pada pagi, siang, dan malam hari sebanyak 100% dan mengonsumsi susu formula pada waktu tersebut sebanyak 82%. Pembersihan rongga mulut setelah mengonsumsi ASI sebanyak 54,5% dan 53% setelah mengonsumsi susu formula. Indeks dmf-t mengonsumsi ASI dan formula masing-masing 5,3 dan 5,4 Simpulan: Persentase ECC balita usia 2-5 tahun yang mengonsumsi ASI lebih banyak mengalami ECC dibandingkan susu formula. Persentase lamanya mengkonsumsi ASI dan formula hampir sama selama 2 tahun. Persentase frekuensi mengonsumsi ASI dan waktu mengonsumi ASI pada pagi, siang dan malam lebih banyak daripada formula serta persentase melakukan pembersihan rongga mulut dan rerata indeks dmf-t hampir sama.Kata kunci: early childhood caries; air susu ibu; susu formula ABSTRACTIntroduction: Early childhood caries (ECC) often occur in Indonesia’s children. Carious lesions on the surface of primary teeth that occur in children aged 2 to 3 years are called ECC because they consume cariogenic foods and beverages. The purpose of the study was to determine ECC in children aged 2-5 years with consumption of breast milk and baby formula. Methods: A descriptive cross-sectional observational study was conducted on the population of 50 children aged 2-5 years. The sampling technique was total sampling, and data was collected using questionnaires and interviews. Data were analysed using Microsoft Excel® software. Results: ECC experienced by children aged 2-5 years were 58% of the total respondents. At the age of 2-3 years, ECC was more experienced by male children and vice versa at 4-5 years. 34% of children aged 2-5 years consume baby formula. 84.8% of the children consumed breast milk for 0-2 years, and 82.4% consumed baby formula. The frequency of breast milk consumption 7-8 times a day was 73%, and the frequency of baby formula consumption of 3-4 times a day was 35.3%. All children (100%) consumed breast milk in the morning, afternoon, and evening, while only 82% of children consumed baby formula in the same consumption time. Oral cleansing was performed by 54.5% of children with breast milk consumption and 53% of children with baby formula consumption. The dmf-t index of children with breast milk and baby formula consumption were 5.3 and 5.4, respectively. Conclusions: The percentage of ECC in children aged 2-5 years with breast milk consumption was higher than children with baby formula consumption. The duration of breast milk and baby formula consumption is almost similar for two years. The frequency and time of consumption in the morning, afternoon, and evening is found more in children with breast milk consumption than baby formula. In comparison, the percentage of oral cleansing and the mean of the dmf-t index was almost similar in both consumption groups.Keywords: early childhood caries; breast milk; baby formula