Iwo Jima was certainly a bloody fight with a higher toll. However I believe that the assault on Betio island at Tarawa produced a higher casualty rate - approximately 1,000 Marines and Navy KIA in the 3 day battle, with total casualties of about 3,400. At that rate, Iwo's approximate 6,000 KIA and 28,000 total casualties over the 36-day battle would have escalated to about 12,000 KIA and over 40,000 total casualties - and this tally of bloodshed doesn't include Japanese losses on either island. Of course, comparing losses from one battle to another is just a pissin' contest - ultimately pointless in the grand scheme of things.