This study evaluated the physiologic status of 155 loggerhead sea turtles (Caretta caretta) that stranded on Cape Cod, Massachusetts, between 2008 and 2016 after exposure to naturally cold temperatures. One hundred thirty-five turtles (87%) survived to be released into the wild, whereas 20 turtles (13%) died during the first week of hospitalization. Comparisons of the initial data for turtles that died vs. those that survived indicated that turtles that died had significantly higher blood glucose, potassium, lactate, and partial pressure of carbon dioxide as well as significantly lower pH, partial pressure of oxygen (pO₂), heart rate, and respiratory rate. Convalescent data for 80 turtles were acquired 10.5 days (median) after admission (interquartile range: 6–17 days; range: 5–66 days). Convalescent turtles had significantly higher body temperature, blood urea nitrogen (BUN), sodium, chloride, pH, pO₂, and ionized calcium (iCa), as well as significantly lower glucose, lactate, and bicarbonate. BUN, pH, and iCa were positively correlated with the number of days in the hospital, whereas glucose and lactate were negatively correlated. Results of this study indicate that the majority of cold-stunned loggerhead sea turtles had a favorable prognosis with medical management. More severely affected turtles showed a variety of physiologic derangements and had a worse prognosis.