Telomere length was sequentially determined in peripheral blood leukocytes (PBL) from patients with ankylosing spondylitis (AS; n = 44) and psoriatic arthritis (PsA; n = 42) followed through 2.93 ± 0.99 years, using a quantitative PCR (qPCR) assay. The initial telomere size from PsA patients was higher than those with cutaneous psoriasis only (n = 53), possibly due to the inflammatory condition. The qPCR assay was sensitive enough to evidence a significant telomere length shortening in PBL from practically all subjects and PsA patients showed a higher rate of loss of telomere sequence than patients with AS during the follow-up time.