The same quandary faces the researcher who wishes to become acquainted with the biologic activity characteristic of some pyrazolo[3,4-d]pyrimidines. There thus seemed to be a place for a book that would cover specifically the chemical manipulations involved in the synthesis of pyrazolo[3,4-d]pyrimidines. A book then was intended that would supplement both the available medicinal and organic chemistry texts. Comprehensive coverage of both the preparation and biologic activity of all pyrazolo[3,4-d]pyrimidines reported in the literature to show such activity would lead to a truly enormous treatise. Also, a book was then extend to explain a new methods for synthesis and biological activity of some new heterocyclic systems containing pyrazolo[3,4-d]pyrimidines. The structure of these compounds was established on the basis of their elemental analysis and spectral data. The synthesized compounds are tested in vitro for their antimicrobial activity compared with the standard antibiotics Ampicillin and Tarivid, and fungicide Mycostatin.