Laver belongs to the genius of Porphyra and is the most valuable seaweed in the aqua-culture industry. It contains higher iron than many other plant foods. The bioavailability of iron from laver was evaluated in a rat hemoglobin regeneration assay. Reagent-grade ferrous sulfate was used as the reference standard, and the relative biological value (RBV) for laver was expressed as a percentage of the response to ferrous sulfate. RBV was calculated by two methods: slope-ratio and ratio of hemoglobin regeneration efficiency, and both yielded RBV of 26 for laver. Amount of available iron from laver estimated from RBV was comparable to many iron-fortified foods.