Oesophageal transit was studied in 49 healthy volunteers. When a good quality bolus was reached, the tracer passed through the oesophagus leaving no residual activity. The mean time of transit of the total oesophagus was 4.5 +/- 1.3 s. In cases of fragmented bolus, residual activity was found in about 80% of the cases giving rise to a prolonged transit time. When using 81Krm, artefacts due to fragmented bolus can easily be overcome by repeating the test as often as necessary.