From the clinical point of view patients with IgA nephropathy present two main symptoms. Some patients have episodes of macroscopic hematuria, either isolated or recurrent, while others present only asymptomatic urinary abnormalities. Although these differences could be due to age-related, geographical or other unknown reasons, in this paper we studied whether patients with these two clinical manifestations differ in some IgA immunological aspects, described occasionally as abnormal in this disease. The following results were obtained: patients having a history of macroscopic hematuria episodes (n = 29) had a significant increase in the percentage of blood polymeric-IgA-producing cells (68 +/- 12%) and in the T cells with IgA Fc-receptors (T alpha cells; 14.5 +/- 3%) in relation to those having only asymptomatic urinary abnormalities (n = 13; 48 +/- 11 and 11.8 +/- 3%, respectively). However, there was no difference in the two groups of patients in relation to the serum IgA levels, percentage of IgA-bearing cells, in vitro synthesis of IgA, T-cell subpopulation and generation of Con A-IgA suppressor cells. Since these patients did not differ in the age of the apparent onset of the disease, in age at the moment of the study or in the activity of the disease determined by hematuria, our results afford an immunological support suggesting the existence of two subgroups of patients with IgA nephropathy.