Fifty patients with perennial allergic rhinitis and extrinsic allergic asthma were studied to determine the relative percentages of OKT3+, OKT4+ and OKT8+ cells as well as the OKT4+/OKT8+ ratios. The percentages of the OKT3+ cells (66 +/- 7) were reduced when compared with those of 50 healthy controls (72 +/- 6), (p less than 0.001). The mean values and deviations of the OKT4 marker produced no statistically significant differences between the patient group (44 +/- 6) and the control group (44 +/- 6). A reduction in the OKT8+ marker in the patient group was registered (20 +/- 6), (p less than 0.001). The OKT4+/OKT8+ ratio was, as a result, raised in the patient group (2.3 +/- 0.6) in relation to the control group (1.6 +/- 0.3). The reduction in the OKT3+ cells together with the imbalance in the subset inducer-helper/cytotoxic-suppressor in allergic respiratory disease could lead to non-regulation of B cells and to hyperproduction of IgE.