Experimental support was sought for the alleged dermal sensitization properties of acrolein (107028) by evaluating the ability of acrolein to induce allergic contact dermatitis in healthy female Hartley-guinea-pigs. Concentrations of acrolein in distilled water used for the intradermal and topical induction phases and for the topical challenge phase were 0.01%, 2.5%, and 0.5%, respectively. Neither the 15 acrolein exposed animals nor the same number of vehicle treated controls produced positive skin reactions when challenge tested with acrolein. Sensitization was noted in each of the 15 guinea-pigs treated with 1-chloro-2,4-dinitrobenzene (97007). The authors caution, however, that while the negative results suggest a low risk of developing allergic contact dermatitis from chronic dermal exposure to acrolein, such exposures are most often accompanied by exposures to formaldehyde and other short chain saturated aliphatic aldehydes which can cause allergic contact dermatitis. The authors conclude that workers should be told that there is a potential risk of developing nonirritant dermatitis when working with acrolein, particularly if they have a history of being atopic or have known sensitivities to formaldehyde.