Disclosed are water soluble compositions of paclitaxel and docetaxel formed by conjugating the paclitaxel or docetaxel to a water soluble polymer such as poly-glutamic acid, poly-aspartic acid or poly-lysine. Also disclosed are methods of using the compositions for treatment of tumors, auto-immune disorders such as rheumatoid arthritis. Other embodiments include the coating of implantable stents for prevention of restenosis.