Objectives The purpose of this study is to find the influential clinical and physical characteristics which affect apnea-hypopnea index (AHI) in suspected obstructive sleep apnea (OSA) patients. Methods We evaluated the comprehensive factors including sleep related symptoms, clinical scales, medical history, substance use, and anthropometric data of the 119 participants who complained of the symptoms of OSA. All the participants underwent attended-full night laboratory polysomnography. The correlation and multiple regression analysis were conducted to find the influential and predictive factors of AHI. Results A multiple linear regression model 1 showed that higher AHI was associated with higher body mass index (BMI)(p < 0.001) and higher frequency of observed apnea (p = 0.002). In multiple linear regression model 2, AHI was associated with higher BMI (p < 0.001) and loudness of snoring (p = 0.018). Conclusions The present preliminary results suggest that BMI and observed apnea are most influential factors that affect AHI in suspected OSA patients. In the future study we will design the prediction formula for the OSA and AHI, which is useful in the clinical medical field.