Three adult dogs were evaluated following oral administration of phenol by the owner. All three dogs experienced severe oral and gastric ulceration. Hematological abnormalities included neutropenia with the presence of toxic neutrophils, thrombocytopenia, and increased muscle enzymes. Endoscopic examination was performed, and biopsies yielded a diagnosis of gastric mucosal necrosis in two of the dogs. Following supportive care, the dogs recovered completely. Phenol is a caustic, highly poisonous derivative of coal tar. The dogs of this report were poisoned inadvertently by their owner who received misinformation concerning the use of this chemical via the Internet.