Abstract: Smoking is one of the factors causing decline of lung function characterized by impairment of Forced Expiratory Volume in 1 second (FEV1), Forced Vital Capacity (FVC), and FEV1/FVC. This study was aimed to obtain the differences in FEV1 between smokers and non smokers, among smokers based on duration of smoking, and among smokers based on the number of cigarettes per day in medical students of University of Sam Ratulangi Manado. This was an observational analytic study. Data were analyzed by using the independent T test and the ANOVA with the F Test. Subjects were 40 males, consisted of 20 smokers and 20 non-smokers. Six smokers had smoked for 2-5 years and 14 smokers had smoked for >5 years. Smoking less than10 cigarettes/day, 10-20 cigarettes/day, and more than 20 cigarettes/day were found in 8, 9, and 3 subjects respectively. The independent T-test showed that there was no significant difference in FEV1 between smokers and non-smokers (p=0.250). The independent T-test also showed that there was no significant difference in FEV1 between smokers of 2-5 years and smokers of more than 5 years (p=0.117). The ANOVA test showed that there was no significant difference in FEV1 between smokers of <10 cigarettes/day, 10-20 cigarettes/day, and >20 cigarettes/day (p=0.481). Conclusion: In this study there were no significant differences in FEV1 between smokers and non smokers, among smokers based on duration of smoking, and among smokers based on the number of cigarettes per day.Keywords: smoker, non smoker, FEV1, duration of smoking, number of cigarette Abstrak: Merokok adalah salah satu faktor penyebab penurunan fungsi paru yang ditandai oleh penurunan nilai volume Forced Expiratory Volume in 1 Second (FEV1), Forced Vital Capacity (FVC), dan rasio FEV1/FVC. Penelitian ini bertujuan untuk mengetahui perbedaan FEV1 antara subjek perokok dan non perokok, antar subjek perokok berdasarkan lama merokok, dan antar subjek perokok berdasarkan jumlah batang rokok yang dihisap per hari pada mahasiswa Fakultas Kedokteran Universitas Sam Ratulangi. Jenis penelitian ialah observasional analitik dengan uji T independent dan uji ANOVA dengan uji F. Subjek penelitian ialah 40 orang laki-laki terdiri dari 20 subjek perokok dan 20 subjek non perokok. Hasil penelitian mendapatkan terdapat 6 subjek perokok yang telah merokok selama 2-5 tahun dan 14 subjek telah merokok selama >5 tahun sedangkan yang menghisap rokok <10 batang/hari, 10-20 batang/hari, dan >20 batang/hari ialah masing-masing 8 orang, 9 orang, dan 3 orang. Uji T-independent menunjukkan tidak terdapat perbedaan bermakna antara FEV1 subjek perokok dan non perokok (p=0,250). Hasil uji T independent terhadap perbedaan FEV1 subjek perokok yang telah merokok 2-5 tahun dengan yang telah merokok >5 tahun mendapatkan p=0,117. Uji ANOVA terhadap perbedaan nilai FEV1 antara subjek perokok yang menghisap rokok sebanyak <10 batang/hari, 10-20 batang/hari, dan >20 batang/hari mendapatkan p=0,481. Simpulan: Pada penelitian ini tidak terdapat perbedaan bermakna antara FEV1 subjek perokok dan non perokok, antar subjek perokok berdasarkan lama merokok, dan antar subjek perokok berdasarkan jumlah batang rokok yang dihisap per hari.Kata kunci: perokok, non perokok, FEV1, lama merokok, jumlah batang rokok