Latar Belakang: Stroke sering dianggap sebagai penyakit yang menyerang usia tua, namun angka kejadian stroke kini justru meningkat pada usia muda. Salah satu faktor risiko stroke adalah merokok, yang terbukti menurunkan fungsi endotel, memicu pembekuan darah, hingga menyebabkan aterosklerosis. Hubungan antara merokok dengan tingkat keparahan stroke berdasarkan National Institutes of Health Stroke Scale (NIHSS) masih belum konsisten. Tujuan Penelitian: Mengetahui hubungan antara merokok dengan tingkat keparahan stroke berdasarkan NIHSS pada usia muda. Metode Penelitian: Menggunakan desain studi potong lintang. Data dikumpulkan melalui rekam medis sejumlah 55 sampel dan dipilih melalui teknik purposive sampling, lalu diolah menggunakan SPSS versi 23.0 dan dianalisis menggunakan metode chi-square. Variabel yang bermakna dianalisis lebih lanjut dengan analisa multivariat logistik. Hasil Penelitian: Subjek penelitian merupakan pasien stroke di Siloam Hospitals Lippo Village berusia 20-50 tahun, di mana jenis kelamin laki-laki (54.5%) dan didominasi usia 40-50 tahun (76.3%). Didapati 41,8% pasien memiliki stroke sedang berat, sedangkan 58,2 % stroke ringan. Sebagian besar pasien dalam penelitian adalah pasien stroke iskemik (61,8%) dengan faktor risiko merokok didapatkan pada 38.2% subjek, sementara hipertensi pada 69%, fibrilasi atrium dan dislipidemia 27,2%, lalu diabetes melitus pada 36,4% subjek. Terdapat hubungan signifikan antara merokok dengan tingkat keparahan stroke yang lebih tinggi berdasarkan NIHSS pada pasien usia 20-50 tahun setelah disesuaikan dengan variabel lain (OR=8,568, 95%CI=1,795-40,891;p-value=0,007). Pada analisis v multivariat didapatkan bahwa fibrilasi atrium juga memiliki hubungan signifikan dengan NIHSS yang lebih tinggi. Kesimpulan: Terdapat hubungan bermakna antara merokok pada usia muda 20-50 tahun dengan tingkat keparahan stroke yang lebih tinggi berdasarkan NIHSS. Kata Kunci: Merokok, stroke, NIHSS. / Background: Stroke is often considered a disease that attacks old age, but the incidence of stroke is now increasing at a young age. One of the risk factors for stroke is smoking, which has been shown to reduce endothelial function, trigger blood clots, and cause atherosclerosis. The relationship between smoking and stroke severity based on the National Institutes of Health Stroke Scale (NIHSS) is still inconsistent. Research Objectives: To determine the relationship between smoking and stroke severity based on the NIHSS at a young age. Research Method: Using a cross-sectional study design. Data was collected through medical records of 55 samples and selected using a purposive sampling technique, then processed using SPSS version 23.0 and analyzed using the chi- square method. Significant variables were further analyzed using logistic multivariate analysis. Result: The research subjects were stroke patients at Siloam Hospitals Lippo Village aged 20-50 years, where the gender was male (54.5%) and predominantly aged 40-50 years (76.3%). It was found that 41.8% of patients had moderate to severe strokes, while 58.2% had mild strokes. Most of the patients in the study were ischemic stroke patients (61.8%) with the risk factor of smoking being found in 38.2% of subjects, while hypertension in 69%, atrial fibrillation and dyslipidemia in 27.2%, then diabetes mellitus in 36.4% of subjects. There is a significant relationship between smoking and higher stroke severity based on the NIHSS in patients aged 20-50 years after adjusting for other variables (OR=8.568, 95%CI=1.795-40.891; p-value=0.007). In multivariate analysis, it was found that atrial fibrillation also had a significant association with higher NIHSS. vii Conclusion: There is a significant relationship between the risk factor of smoking at a young age of 20-50 years and a higher level of stroke severity based on the NIHSS. Keywords: Smoking, stroke, NIHSS.