The purpose of this study was to document the histology of canine acupoints. Acupunctural needles were inserted by 0.5 to 1 cm depth into acupoints Nei-guan (Inner pass, PC06), Gan-shu (Liver Association Point, BL18), Shen-shu (Kidney Association Point, BL23) and Pangguang-shu (Bladder Association Point, BL28) in 4 dogs, and the tissues around the acupoints were examined. Light microscopy was used to observe the surrounding structures of each point. Nerve fibres, small vessels and muscle spindles were found around the tip of the needle in every case, although they occurred not so often at nonacupoint in nearby region or nonacupoint in the areas, such as skin, subcutaneous tissue and muscle. Therefore, it is suggested that nerve fibres, small vessels and muscle spindles may be potential acupoint receptors.