Most cetacea available for internal sampling in recent times have died through mass or single stranding events. It is important to know how the time elapsed between death and sampling affect quality of tissues. This study evaluated histological quality in the liver of long-finned pilot whales that either died or were euthanased after mass stranding events. Histological detection of significant autolysis was found in animals when 2 or more hours elapsed between death and sampling. In addition, hepatocytes often had marked idiopathic cytoplasmic vacuolation that did not stain with hematoxylin and eosin. The extent of this vacuolation did not show any correlation with time between death and sampling, but did appear more often in animals of greater total length. These observations suggest that when animals die or are euthanased at a single or mass stranding, every effort should be made to obtain samples as soon as possible, although meaningful histological observations can still be made in the presence of significant autolysis. These data also suggest that a multi-disciplinary study should be conducted to determine whether increasing autolysis is associated with changes in the organic chemical residues, molecular biology, histopathology and microbiology of those tissues.