Infection with Soil-Transmitted Helminths (STH) remains a public health issue among school-aged children in tropical areas. This study aims to analyze the relationship between Clean and Healthy Living Behavior (PHBS) and the incidence of helminthiasis in Medan Marelan District. A quantitative observational study with a cross-sectional design was conducted involving 320 elementary school children. Stool samples were examined using direct microscopy and sedimentation methods, while questionnaire interviews and environmental observations were used to assess PHBS indicators. The results showed a very low prevalence of helminthiasis at 0.62% (2 positive cases out of 320 respondents with Ascaris lumbricoides and Blastocystis hominis co-infection). Basic sanitation facilities were well-maintained (100% pour-flush toilets), and participation in routine mass drug administration (POMP) reached 100%. Statistical analysis using Fisher's Exact Test showed no significant association between shoe-wearing habits, knowledge levels, or gender and helminthiasis infection (p = 1.000). However, a significant knowledge gap was identified, as 66.56% of respondents were unaware of helminthiasis and 100% did not recognize its link to anemia and stunting. In conclusion, low infection prevalence is driven by structural sanitation and mass deworming, but targeted health education is necessary to sustain elimination.