Time and temperature effects on postmortem vitreous humor from 60 adult mongrel dogs were studied. After death the dogs were held at 4, 20, or 37 degrees C for intervals of 3, 6, 12, 24, or 48 h. Antemortem and postmortem vitreous was analyzed for sodium, chloride, potassium, urea nitrogen, glucose, and creatinine. Potassium levels rose with increases in temperature and time. Sodium, chloride, and urea nitrogen values were stable at 4 degrees C for 48 h; they were less stable at higher temperatures. Glucose dropped to less than half within 3 h at all temperatures. Creatinine values were inconsistent. In that postmortem glucose and sodium levels remained below antemortem levels, diagnosis of hyperglycemia and hypernatremia should be possible. Consequently, a diagnosis of hypoglycemia could not be supported; the diagnosis of hyponatremia could be made in the early postmortem period.