Recent studies of T-cell clonal repertoires of patients with ankylosing spondylitis (AS) have led to the discovery of AS-associated T-cell clones with a highly homologous T-cell receptor structure. The role of T-lymphocytes in the disease progression cannot be elucidated without analyzing the diversity and abundance of functionally different T-cell clones found in patients with AS. Using a state-of-the-art technique for T-cell repertoire profiling based on massively parallel sequencing, we, for the first time, studied the T-cell receptor repertoire of activated T-cells from the peripheral blood of a patient with AS. We have demonstrated that a subpopulation of CD38⁺HLA-DR⁺ T-lymphocytes is highly diverse both in terms of clonal diversity and abundance of the identified clonotypes, suggesting diverse antigen specificity of the activated peripheral blood T-cells. Most of the activated T-cell clonotypes had low abundance in total population of peripheral blood T-cells. In the repertoire of activated T-cells we have found the clonotype TRBV9_CASSVGVYSTDTQYF_TRBJ2-3, previously discovered in AS and reactive arthritis, and a few other clonotypes of cytotoxic and helper T-cells that may have a role in promoting inflammation in AS patients. Presence of the AS-associated clonotype in activated T-cell subset suggests that the T-cells might play an active role in ongoing inflammation during the disease progression. This provides rationale for further research of their antigen specificity and role in triggering or maintaining AS.