Certain fluorenone and anthraquinone compounds, each of which is 2-substituted by a carboxyl group or a salt, ester or optionally substituted amide thereof and each of which is optionally substituted in the 5,6-,7-or 8-position, by a second carboxyl group, salt, ester or optionally substituted amide thereof, the substitutent in the 5,6-7- or 8-position of the fluorenone compounds, also being selected from cyano, halogen, nitro, alkyl, alkoxy and acyl, are useful for the relief or prophylaxis of allergic conditions.