This specification describes the physical requirements and corresponding test methods for disposable glass blood sample capillary tubes for use in microhematocrit procedures. Covered here are two different types of capillary tubes, namely, Type I (coated with heparin), and Type II (uncoated). The tubes shall be fabricated from Type I, Class B borosilicate glass, or Type II soda lime glass. Conversely, the heparin used for coating Type I tubes shall be of ammonium salt isolated from the lungs or intestinal mucosa of beef or pork origin. The tubes shall conform to specified requirements for design, dimension, workmanship, color coding, and lot or control number. They should also pass the following tests for capillarity, fluidity, sheep plasma, positive and negative controls, human whole blood, heparin potency assay, and resistance to centrifugal force.