Diagnosis of otitis media is based on detection of middle-ear fluid (MEF) and is both important and difficult to achieve. Also non-infectious MEF is important to detect, since it can compromise hearing. In this prospective, blinded study, spectral gradient acoustic reflectometry (SG-AR) was evaluated as an indicator of MEF among children. Sensitivity, specificity and positive and negative predictive values of SG-AR in detecting MEF were calculated in children undergoing ambulatory surgery for recurrent or secretory otitis media using otomicroscopic myringotomy as the reference method of confirming middle-ear status. Final study material consisted of 376 ears. Pattern recognition of SG-AR curves reached the best combination of sensitivity and specificity (69 and 97%, respectively), and the best combination of positive (PPV) and negative (NPV) predictive values (93 and 83%, respectively), in detection of MEF. With a spectral gradient value of <80 degrees , the sensitivity was 75% and specificity 71%. With <50 degrees , PPV was 78%, and with >or=100 degrees , NPV was 86%. The diagnostic power of SG-AR was comparable to that reported with pneumatic otoscopy and tympanometry. It was equally effective in detecting both MEF cases and healthy ears. Pattern recognition seems to improve its performance. We recommend the use of pattern recognition of SG-AR as a screening method for MEF among children.