The goal of this study was to review published data on iron status among vegetarian adults. Thirteen original articles met the inclusion criteria. Among female vegetarians, the percentage of the sample with ferritin <12 µg/L or <12 ng/mL ranged from 12% to 79%. An inadequate hemoglobin concentration ranged from 6% to 30.3%. Among males, the range of ferritin <12 µg/L across studies was from 1.7% to 29%. The prevalence of hemoglobin below deficiency cutoff ranged from 0% to 15.3%. A higher percentage of vegetarian females, compared to nonvegetarian participants, had ferritin below deficiency cutoff in all but one study (34% vs 0%, 47% vs 42%, 18% vs 13%, 27.8% vs 6.5% among Catholic nuns and 19.4% among college students, 79% Indian, and 56% Caucasian vegetarian vs 27% of nonvegetarian). Serum ferritin was lower in male vegetarians than male nonvegetarians in each study (11% among vegans and 21% among vegetarians compared to 6% and 7% among high and moderate meat consumers, 3% of vegetarians, and 25% vegans vs 0% of nonvegetarians, 29% vs 7%, 9% vs 0%). Vegetarians have a high prevalence of depleted iron stores. A higher proportion of vegetarians, compared to nonvegetarians, had iron deficiency anemia. This is especially true for premenopausal vegetarian women.