Certain parts of shellfish contain poisonous substances and cause intoxication. Tetramine toxin is found in the salivary gland of Neptunea. Three family members were admitted to the hospital with chief complaints of dizziness and blurred vision, gait disturbance, and spasms of the lower extremities after ingesting Neptunea. Physical examination revealed sluggish pupil light reflexes, but laboratory studies were normal. Symptoms were completely resolved within 24 hours after injection of atropine. We report a case of three patients with dizziness and blurred vision, gait disturbance, and spasms of the lower extremities due to Neptunea tetramine toxin.