Introduction: Nonerosive gastroesophageal reflux disease (NERD) is the most common gastroesophageal reflux disease (GERD) and is associated with acid, weakly acid, nonacid, liquid, and mixed reflux. The present study aimed at evaluating the differences among gastroesophageal reflux patterns, number of reflux episodes and its composition in patients with NERD using combined multichannel intraluminal impedance-pH (MII-pH) monitoring tool in the Iranian population. Materials and Methods: This study was conducted on 670 participants aged 11 to 65 years, with nonerosive gastroesophageal reflux disease (NERD). They were selected using a questionnaire and esophagogastroduodenoscopy findings. Esophageal multichannel intraluminal impedance-pH (MII-pH) monitoring test was performed for all the patients. The number of reflux episodes and their composition, DeMeester score, symptom index (SI), and symptom associated probability (SAP) were recorded. Results: Of 670 patients who had NERD, 49.5% (332/670), 65.1% (436/670), and 4.0% (27/670) had acid, weakly acid, and nonacid reflux, respectively. Moreover, 11.8% (79/670), 89.2% (598/670), and 77.5% (519/670) had liquid, mixed, and gas reflux, respectively. DeMeester scores were above the normal range in 39.4% (264/670) of the patients. The symptom index (SI) and symptom-association probability (SAP) score, regardless of PH, were 34.6% (232/670) and 58.4% (391/670) above the normal range, respectively. Conclusion: The present study revealed that weakly acid reflux was more prevalent in patients with nonerosive reflux disease (NERD) than in those with acid or nonacid reflux. Also, gas (and mixed) reflux was more frequent than liquid reflux. No significant difference was found between upright and supine position of acid, weakly acid, and nonacid reflux in patients with NERD (P>0.05). The diagnostic value of the DeMeester score, symptom index (SI), and symptom associated probability (SAP) was less than 50%.