Gastro-oesophageal reflux (GOR) disease may cause excessive crying in infants. The role of GOR was evaluated in infant irritability and an attempt was made to define clinical predictors of pathological reflux. Seventy consecutively admitted infants with irritability and presumptive GOR were retrospectively reviewed. All had undergone prolonged oesophageal pH monitoring. Pathological GOR was defined as a fractional reflux time of > or = 10% and was significantly less common in infants under 3 months (one of 24; 4.2%) than in older infants (10 of 46; 21.7%). All infants with pathological GOR presented with frequent vomiting, and 'silent' pathological reflux did not occur. Poor weight gain, feeding refusal, backarching, and sleep disturbance were not significantly associated with pathological GOR. The results suggest that pathological GOR is an unlikely cause of infant irritability under the age of 3 months.