The present invention relates to new functionalized 9-bromo-camptothecin derivatives (I) which have cytotoxic activity and are useful in treating diseases such as cancer, cellular proliferation disorders and viral infections. The present invention also provides methods for preparing these compounds, pharmaceutical compositions comprising them and methods of treating diseases utilizing such compounds or the pharmaceutical composition containing them. The invention also relates to the use of these functionalized 9-bromo-camptothecin derivatives in the preparation of conjugates.