Fluorescent dyestuffs of the general formula ##STR1## wherein R and R.sup.1 independently of one another represent hydrogen, a salt-forming cation, an alkyl radical with 1 to 16 C atoms or an aryl or aralkyl radical which is optionally substituted by non-chromophoric groups,R.sup.2 to R.sup.5 independently of one another represent hydrogen, alkyl, trifluoromethyl, alkoxy, aralkoxy, alkenoxy, aryloxy, halogen or a carboxyl, cyano, alkyl sulphone, aryl sulphone, aralkyl sulphone, carboxamide, sulphonamide or carboxylic acid ester group,o, p, q and s independently of one another represent 1 or 2 andm and n independently of one another denote 0, 1 or 2, it being possible for the sum of m and n to be 2 to 4,processes for their preparation and their use as laser dyestuffs.