Platelet storage pool disease (SPD) is a platelet function disorder characterized by a reduction in the number or content of α-granules, dense granules, or both, and is diagnosed by specialized tests. Patients with SPD often present with prolonged bleeding time (BT), but the sensitivity and reproducibility of this test have limitations, often resulting in false negatives. It has recently been reported that an automated microchip flow-chamber system (T-TAS(®)) is useful in the assessment of anti-platelet therapy, and could have potential as a screening test for SPD. We examined the utility of T-TAS in three individuals from one family diagnosed with δ-SPD. The propositus had a mildly prolonged BT, and the standard tests for platelet function were close to the normal range. Whole blood samples were anti-coagulated with hirudin and applied to T-TAS microchips coated with collagen (PL-chips) at shear rates of 1000 and 2000 s(-1). Platelet thrombus formation (PTF) was monitored with a pressure sensor. Markedly depressed PTF was observed in all cases at both shear rates. These findings indicate that T-TAS is highly sensitive to the defect in these patients with SPD, and may represent a good candidate screening test for a wide range of platelet function disorders.