OBJECTIVE: To develop and validate a simple method of measuring total menstrual blood loss using a pictorial representation of blood loss, the menstrual pictogram. DESIGN: A prospective evaluation of total menstrual blood loss measurement by the menstrual pictogram compared to the alkaline hematin technique. SETTING: Academic menorrhagia research clinic. PATIENT(S): One hundred twenty-one women; 62 women complaining of heavy menstrual blood loss, 59 women who considered their menstrual blood loss to be normal. INTERVENTION(S): Participants were asked to complete the menstrual pictogram through the period and collect their feminine hygiene products for an alkaline hematin assessment. MAIN OUTCOME MEASURE(S): Percentage agreement between blood loss measured by the gold standard alkaline hematin method and the menstrual pictogram. Extraneous blood loss was measured using a semiquantitative pictorial method. RESULT(S): The menstrual pictogram had a high level of agreement for blood collected on feminine hygiene products compared with the alkaline hematin method. Some women also lose a significantly large amount of extraneous blood, which is not proportional to the alkaline hematin blood loss assessment. CONCLUSION(S): The menstrual pictogram provides a simple means of measuring menstrual blood loss. It is no longer appropriate to ignore extraneous blood loss, particularly as there is no correlation between extraneous blood loss and that measured on feminine hygiene products.