Infeksi Saluran Pernapasan Akut (ISPA) merupakan penyebab utama morbiditas dan mortalitas pada anak di bawah usia 5 tahun (balita). Pengetahuan orang tua tentang pencegahan ISPA berperan penting dalam mengurangi kejadian ISPA pada balita. Penelitian ini bertujuan untuk menganalisis hubungan antara pengetahuan orang tua tentang pencegahan ISPA terhadap kejadian ISPA pada balita di wilayah kerja Puskesmas Legok, Tangerang. Penelitian dilaksanakan pada bulan April 2025. Penelitian ini menggunakan metode penelitian kuantitatif dengan desain cross-sectional. Sampel pada penelitian ini berjumlah 93 responden. Pengumpulan data menggunakan kuesioner yang telah diuji Content Validity Ratio (CVR) dan Content Validity Index (CVI) dan catatan rekam medis responden. Analisis data dilakukan menggunakan uji chi-square. Hasil penelitian ini menunjukkan 70 responden (75,3%) memiliki tingkat pengetahuan baik dan 55 balita (59,1%) mengalami ISPA dua bulan terakhir. Terdapat hubungan antara tingkat pengetahuan orang tua tentang pencegahan dengan kejadian ISPA pada balita dengan p-value 0,037. Saran bagi peneliti selanjutnya untuk dapat mencari faktor faktor lain yang memengaruhi kejadian ISPA pada balita yang belum diteliti, seperti kondisi lingkungan, status imunisasi, status gizi, serta sanitasi yang belum optimal. / Acute Respiratory Infections (ARI) are major cause of morbidity and mortality in children under five years of age. Parental knowledge about ARI prevention plays an important role in reducing the incidence of ARI in children under five years of age. This study aimed to analyze the relationship between parental knowledge about ARI prevention and the incidence of ARI in children under five years of age in Puskesmas Legok, Tangerang. This study was conducted in April 2025. This study used quantitative methods with a cross-sectional design. The sample in this study were 93 respondents. Data collection used a questionnaire that had been tested for Content Validity Ratio (CVR) and Content Validity Index (CVI) and respondent’s medical records. Data analysis was carried out using the chi-square test. The results of this study showed that 70 respondents (75,3%) had a good level of knowledge and 55 children under five years of age (59,1%) had experienced ARI in the last two months. There was a relationship between the level of parental knowledge about ARI prevention in reducing the incidence of ARI in children under 5 years of age with p-value of 0,037. Suggestion for further researchers is to find other factors that influence the incidence of ARI in children under five years of age, such as environmental conditions, immunization status, nutritional status, and suboptimal sanitation.