PURPOSE: To obtain a new benzo[a]fluorene compd. having estrogenic activity and anti-estrogenic activity and useful in anti-estrogen therapy, anti-reproductive potential therapy, anti-neoplasm therapy, the prevention of bone damage, etc.

CONSTITUTION: The benzo[a]fluorene compd. is a compd. of formula I [where R is hydroxy or -O-(CH2)n-N(R3) (R4) (1≤n≤3 and R3 and R4 are each a 1-4C alkyl or R3 and R4 together form butylene, pentylene or hexylene); R1 is H, hydroxy, a 1-3C alkoxy, etc.; and R2 is H, hydroxy, a 1-3C alkoxy, etc.], e.g. 9-ethoxy-11-[4-(2-hexamethylenimin-1-ylmethoxy)phenyl]-11H-benzo[a]fluorene. The compd. of the formula I is obtd., e.g. by allowing a compd. of the formula I (where R is hydroxy) to react with an alkylating reagent of formula II (where X is a releasable group).