Although HTLV-I infection has been associated with immunosuppression in symptomatic patients, no controlled study has been done in asymptomatic carriers. We evaluated delayed-type hypersensitivity (DTH) to seven antigens by multitest cell-mediated immunity (CMI) in 40 Colombian Indians, 10 HTLV-I-seropositive asymptomatic patients, and 30 matched controls. Multitest CMI was placed in the forearm and was read 48 hours later by the same physician. A positive reaction was defined as ≥2 mm. Hypoergic response was defined as <2 of 7 positive reactions per case or control. We found that HTLV-I-seropositive people had fewer positive reactions than matched controls (50% versus 64%, respectively; p < .04) but no significant difference was found in these populations in the evaluation of hypoergic responses. This study suggests the presence in asymptomatic HTLV-I-positive Colombian Indians of a marginal alteration of cell-mediated immunity that cannot be classified as hypoergic.