The structure of cyclomicrobuxine (Ia) has been confirmed by the interrelation achieved with the known alkaloid cyclobuxine-D (IV). The isolation and structure of another new alkaloid, cyclomicrobuxinine (Ib), from Buxus microphylla Sieb. et Zucc. var. suffruticosa Makino, is also described. Alkaloid-L (VIa), isolated from Buxus microphylla Sieb. et Zucc. var. suffruticosa Makino forma major Makino, has been correlated chemically with the known alkaloid cyclomicrophylline-A (VIII).