Pyrazolo[3,4-d]pyrimidine ring system constitute an important class of heterocyclic compounds which can serve as a promising scaffold exhibiting many pharmacological activities. This ring system received much attention as it is a purine isostere by replacing imidazole ring in purine with pyrazole moiety in pyrazolo[3,4-d]pyrimidine. Here we concentrate on new advances in the synthesis of this important ring and other clinical aspects in an attempt to sheld the light to assist in discovery of new pyrazolo[3,4-d]pyrimidine derivatives.