Faecal impaction with or without encopresis is a very common problem. We performed a randomized, open-label, prospective study to compare the efficacy and acceptability of the treatment of faecal impaction using either mineral oil or pineapple-flavoured isotonic intestinal lavage solution containing polyethylene glycol-3350 (Colyte). Thirty-six patients over 2 years of age were randomized to receive either mineral oil or flavoured lavage solution. The dose of mineral oil was 2 to 8 tablespoons twice a day for two days (17 patients--Group I) and of lavage solution was 20 ml/kg/h for 4 hours on two consecutive days (19 patients--Group II). The patients were assessed for the presence of abdominal faecal masses, presence and consistency of rectal mass, perineal soiling before and two days after either of the randomly assigned treatment. The patients and parents were asked regarding the compliance with treatment, side-effects, number of bowel movements after treatment and willingness to try similar treatment if faecal impaction recurred. Patients in the lavage group had more frequent bowel movements, and showed more effective clearance of abdominal and rectal lumps (P < 0.01) at the time of repeat examination at two days. However, they had some vomiting and were less compliant (P < 0.01) when compared to mineral oil patients. We conclude that balanced lavage solution effectively relieves faecal impaction, however, compliance with its use is poorer than that with mineral oil.