Abnormal bleeding or bruising is frequently encountered in the clinical practice of dermatology. A working knowledge of mechanisms of normal hemostasis, a complete history (general, bleeding, familial), a thorough physical examination, and an appropriate laboratory evaluation are the integral steps in the diagnostic process. Cutaneous bruising and/or bleeding may be a manifestation of a previously unrecognized hereditary coagulation deficiency such as mild hemophilia or von Willebrand's disease (vWD), hereditary or acquired qualitative or quantitative platelet disorder, disturbance of the vascular or supporting structure, or it may be due to one of several acquired systemic disorders.