Background To obtain reliable and accurate measurements of the intraocular pressure (IOP) in children often requires sedation or anaesthesia. Therefore, we investigated the effects of oral midazolam on IOP in children. Methods In a prospective study, IOP was measured in 72 eyes of 36 cooperative children without glaucoma requiring general anaesthesia (mean age 3.5 +/- 1.3 years, body weight <= 20 kg) by using a Perkins hand-held tonometer. Measurements of IOP were performed before, and 15 and 30 min after sedation with orally administered midazolam (1 mg/kg) given as preoperative medication, and 5 and 15 min after induction of general anaesthesia. The individual IOP courses were analysed. Results In all of the cooperative children, IOP measurement was possible after sedation with midazolam. Mean IOP was 11.2 +/- 0.3 mmHg before sedation, 10.9 +/- 0.2 mmHg at 15 min, and 10.7 +/- 0.3 mmHg 30 min after administration of midazolam. This small decrease was not statistically significant, whilst the IOP decline at 5 and 15 min after induction of general anaesthesia was statistically significant (p<0.0001). Conclusion Sedation with midazolam can be assumed to be an applicable, well-tolerated, safe method for IOP measurements in children.