UNLABELLED: Ineffective esophageal motility (IEM) has been described in patients with gastroesophageal reflux disease (GERD). Exact prevalence of IEM is unknown; however, it is associated with more severe forms of GERD. There are no studies of IEM in patients with non-erosive GERD (NERD). Traditionally, IEM is identified by manometry at 3 and 8 cm above lower esophageal sphincter. Studies evaluating each cm of distal third of esophagus to detect IEM have not been carried out to date. AIM: To determine frequency of an IEM in NERD and erosive GERD as well as in mild and severe esophagitis, and to compare traditional criteria of IEM vs. manometry of each cm of distal third of esophagus. MATERIAL AND METHODS: Healthy controls and patients with NERD and mild and severe esophagitis were studied. Manometry of each cm of lower third of esophagus was performed. Amplitude of esophageal contractions and frequency of IEM were compared between different groups of subjects and patients. The ability to detect IEM by traditional criteria and proposed criteria was determined. RESULTS: Forty-four subjects were included, 13 controls, 10 patients with NERD, 12 with mild esophagitis, and nine with severe esophagitis. Amplitude of contractions was significantly different between groups. Controls showed higher amplitude than patients with severe esophagitis. Frequency of IEM was 0% in controls, 20% in NERD, 17% in mild esophagitis, and 33% in severe esophagitis. Frequency of IEM was similar when traditional criteria and proposed criteria were compared. CONCLUSIONS: IEM occurs in NERD as well as in mild and severe esophagitis, and IEM is associated with GERD severity. Traditional manometry detects similar proportion of patients with IEM as well as manometry of each cm of lower third of esophagus.