Data and its acquisition are the prime components of computational cytology. The data can be classified as Internal and external databases. The internal database is generated from the local hospital or laboratory data. The main components of the internal database are microscopic images, clinical, biochemical, radiological and molecular genetics. The external database is acquired from the medical journals, clinical trials or other databases from the various sources. The complete utilization of both databases can help to make an effective neural network model. The present chapter discusses the various components of the databases.