Ovine IgG was detected in homogenates of repeatedly washed Psoroptes ovis. Some of the immunoglobulin in the homogenates was fragmented although the host IgG present in mite washings was largely intact. The host immunoglobulin was immuno-localised to the surface or cytoplasm of the gut cells of feeding stages of freshly harvested P. ovis examined by cryosectioning. A similar distribution of rabbit IgG was detected in P. cuniculi. The IgG demonstrated in the mite gut represented partially digested as well as intact immunoglobulin. The presence of intact host immunoglobulin suggests that P. ovis may be susceptible to vaccination by the gut antigen approach, a method used successfully for blood-feeding ectoparasites like Boophilus microplus.