OBJECTIVE To determine whether the menstrual pictogram (the superabsorbent polymer-c or SAP-c version) can reliably estimate blood and total menstrual fluid volumes on prestained Always Ultra slim feminine towels (Proctor & Gamble) that contain superabsorbent polymers. DESIGN Randomized blinded study using simulated menstrual fluid (SMF: 50% blood, 50% saline mixture). SETTING Gynecology research clinic. PATIENT(S) 12 premenopausal women with regular menstrual cycles who had not previously used a graphical method to assess menstrual loss. INTERVENTION(S) None. MAIN OUTCOME MEASURE(S) Assignment of 135 prestained towels containing known volumes of 0.5-25.0 mL of SMF to five pictorial icons of the menstrual pictogram, and correlation of pictogram scores to blood recovered from towels by the alkaline hematin method and total fluid applied to towels by measurement of soiled towel weight. RESULT(S) There was a high level of agreement between individual scores. For 112 (83%) of 135 towels, the participants' readings either completely concurred or differed by only a single icon. There was a statistically significant correlation between the volume of blood applied (SMF/2) and that recovered by alkaline hematin, and volume of fluid applied and soiled towel weight. CONCLUSION(S) The menstrual pictogram (SAP-c version) is a potential diagnostic tool for heavy menstrual bleeding and would be suitable for testing in a clinical trial.