Harmful algal blooms caused by Karenia brevis are fairly common along the central west coast of Florida and occasionally sea turtles are admitted with neurological symptoms that are associated with the toxin (brevetoxin) released by the K. brevis organism. During the summer of 2005 a large number of dead and affected turtles stranded from Pinellas to Charlotte Counties, Florida. Live turtles were taken to both Clearwater Marine Aquarium and Mote Marine Laboratory for rehabilitation. Dead turtles were either necropsied at the facilities or were sent to the University of Florida for post-mortem exams. In addition, serial serum samples from live turtles and tissues from dead turtles were tested by ELISA for brevetoxin. These tests indicated that brevetoxin was present in high concentrations and that clearance of the toxin was species specific. Clinically, loggerheads presented comatose with swollen eyes and no eye reflexes whatsoever and responded poorly or not at all to treatment. This is atypical for red toxicosis seen in sea turtles in the past. Other species presented with lesser neurological symptoms that disappeared fairly rapidly once the turtles were removed from the water containing the toxin, which is typical from past episodes. Common necropsy findings, particularly from loggerheads, included severe bacterial infections, interpreted as opportunistic disease, and sea water aspiration. No histopathological changes specifically attributable to toxic injury were observed, which is consistent with natural and experimental brevetoxin exposure in other species.