Hirudo is a genus of leeches of the family Hirudinidae. It was described by Carl Linnaeus in his landmark 1758 10th edition of Systema Naturae.

The two well-accepted species within the genus are:

• Hirudo medicinalis Linnaeus, 1758
• Hirudo nipponia Whitman, 1886

Three other species, previously synonymized with H. medicinalis, were described in 2005 and are gaining acceptance:

• Hirudo verbana
• Hirudo orientalis
• Hirudo sulukii
• Hirudo troctina
• Hirudo tianjinensis

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