Guinea pigs are frequently presented with skin conditions. Common clinical signs of hair loss, pruritus, skin masses, foot lesions or lameness are generally easily visible and detected by owners, which may account for the high proportion of animals presented with skin conditions. As for other small mammals, a full dermatological examination should be undertaken regardless of the reason for presentation, followed by appropriate diagnostic tests to reach a definitive diagnosis if dermatological lesions are detected. This chapter details the differential diagnosis and management of skin diseases in guinea pigs.