To white paraffin containing potassium dichromate in various concentrations (0.5, 0.1, 0.05 and 0.01%) the following emulsifiers were added: 10% glycerol monostearate; 10% Tween 60, and 3% Span 20. Patch tests were performed with these bases and the amount of Cr VI released in vitro was determined. All the three emulsifiers enhanced, though to a different extent, chromium release in vitro from bases containing 0.5% dichromate. In bases containing 0.05 and 0.01%, release was enhanced only by glycerol monostearate. The effect of all three emulsifiers in vivo differed: glycerol monostearate distinctly enhanced, Tween 60 somewhat reduced, and Span 20 did not visibly affect the sensitivity of the patch test.