Six new ent-abietane diterpenoids, rubescensins IM (15) and P (6), along with two related acetonide derivatives (7 and 8), were isolated from Isodon rubescens. Their structures were elucidated by detailed spectroscopic analysis. Compound 5 is the first N-containing diterpenoid from the genus Isodon, exhibiting notable cytotoxicity against human tumor K562 cells.