Smear quality is related to the experience of the sample taker and also to the screening instrument used. Most Authors concur that both an endocervical and an ectocervical specimen must be collected to assure adequate sampling of the transitional zone. The cytobrush alone is effective mainly for endocervical sampling while the Ayre spatula alone is effective mainly for ectocervical sampling; the cotton swab is ineffective for both endocervical and ectocervical sampling. Values and failure of the sampling devices are described.