A double-blind, group comparison trial of a topical cream containing 4% sodium cromoglycate (SCG) was undertaken in forty-six patients with chronic atopic eczema. A statistically significant improvement was seen after 9 weeks in the actively treated patients compared with the placebo group. However, in general, no benefit was observed in severe eczema, perhaps due in some part to the seemingly late onset of action of SCG. Measurement of total serum IgE before and after the trial showed an increase in levels which was apparently unrelated to treatment with SCG or placebo or to a change in severity of the eczema. The amount of SCG in the urine was small and very variable, indicating low percutaneous absorption. The calculated bioavailability ranged from 0.01% to 2.75% of the applied dose. These results together with follow-up studies suggest that topical SCG as a long-term measure may be useful in the management of mild or moderately severe eczema, reducing the frequency of acute exacerbations.