Background: Needle insertion pain associated with maintenance hemodialysis (HD) causes considerable stress on HD patients with native arteriovenous fistula. Skin cooling has been suggested to modify pain sensitivity and reduce needle insertion pain. Recently, a skin cooling device, named Mutsu-Senshi®, has been developed to decrease local skin temperature to 21°C smoothly and safely at the bedside. Therefore, we examined the effectiveness of Mutsu-Senshi® in 4 HD centers in Japan.