Sodium alginate (Gaviscon) is used in the management of gastro-oesophageal reflux in infants. No digestive disadvantages have as yet been reported with the use of the Gaviscon formula available in France, which contains neither aluminium hydroxide nor thickener. Twenty-two healthy neonates were prospectively studied before and after Gaviscon treatment in order to characterize their whole gut transit time with the use of a carmine index. The head of the marker appeared within the same time in both experiments but the appearance of the tail was earlier in the treated infants (P < 0.05), without any subsequent clinical consequences. The slight increase shown in the rate of the clearance of the marker from the gut, is likely to be related to a less proximal to distal dispersion of the marker, subsequently to physical changes occurring in the viscous alginate. Frequency and consistency of the stools were unmodified by treatment and accordingly Gaviscon can be regarded as having no deleterious effect on transit time in neonates.