AbstractRecent developments in the effort to understand the metabolism and function of the intracellular dinucleoside polyphosphates were described by nine speakers from some of the world’s leading laboratories in this field in a workshop at the Purines 2000 International Symposium on Nucleosides and Nucleotides held in Madrid in July, 2000. Topics were wide‐ranging and included phenotypic analyses of yeast mutants defective in enzymes of dinucleoside polyphosphate degradation, virally encoded catabolic enzymes, the structure and function of the Fhit tumor suppressor and Fhit‐nitrilase fusion proteins and the relationship of Fhit to human diadenosine triphosphate hydrolase, site‐directed mutagenesis of diadenosine tetraphosphate hydrolase, novel nucleotide analogs for studying hydrolase function, the synthesis of dinucleoside polyphosphates by ligases, and the possible roles of diadenosine tri‐ and tetraphosphates in insulin function and of diadenosine tetraphosphate in the heat‐shock response of Escherichia coli. The results presented and the ensuing discussions showed that, while considerable progress is being made in the field, it still has the capacity to tease and frustrate and produce the unexpected result. Drug Dev. Res. 52:249–259, 2001. © 2001 Wiley‐Liss, Inc.