AbstractCroton sublyratus (Euphorbiaceae) is a traditional medicinal plant used by the Thai populace to treat helminthic infections and dermatologic conditions. In present study, eight new labdane‐type diterpenoids, crotonoids A–H (1–8) and one known analogue (9) were isolated from the aerial parts of C. sublyratus. Compounds 6 and 7 belong to the rare class of 14,15‐dinor‐labdane diterpenoids. Compound 8 exhibited a rare 14,15,17‐trinor‐labdane skeleton. The structures of all these diterpenoids were elucidated by spectroscopic data analysis, electronic circular dichroism calculations, and single‐crystal X‐ray diffraction analysis. Compound 9 exhibited moderate anti‐inflammatory activity via the inhibition of NO production in lipopolysaccharide‐induced RAW 264.7 cells.