A versatile and highly efficient procedure has been introduced for preparation of spiro pyridodipyrimidines during the investigation of the reaction of 1,3-dimethyl-6- aminouracil with isatin derivatives, ninhydrin, and acenaphthoquinone under classical or microwave-assisted solvent-free conditions.Key words: isatin, ninhydrin, acenaphtoquinone, 1,3-dimethyl-6-aminouracil, solvent-free.