The inhibitory effects of six contact antiphlogistics and two dermatocorticoids on hexadecane-induced hyperplasia of the guinea-pig skin were tested and compared. On the basis of the results obtained, the substances can be ranked in the following order of potency (percent inhibition of surface epithelial proliferation): acetylsalicylic acid (7.9%), phenylbutazone (12.5%), bufexamac (16.4%), bendazac (16.6%), oxyphenbutazone (19.5%), indomethacin (20.0%), hydrocortisone (20.6%) and fluocinolone acetonide (32.0%).