Abstract: Devices, and methods for the use of same, for collecting and assaying a biological fluid in a single step. One method provides means to control and direct the flow of a sample of the biological fluid directly onto an assay test strip by disposing the assay test strip within a flow control channel in which the internal ambient pressure is maintained in substantial equilibrium with the ambient pressure outside of the flow control channel, such that essentially no pressure gradient is formed within the flow control channel. The devices include the flow control channel, at least one assay test strip and a fluid sample collection container, such as a urine cup, for insertion of the flow control channel therein.