BACKGROUND Long noncoding RNAs (lncRNA) NF-kappaß-interacting long noncoding RNA (NKILA) is downregulated in various types of cancers, while its involvement in other diseases is unknown. In the present study we found that plasma lncRNA NKILA was expressed at higher levels in active ankylosing spondylitis patients than in healthy controls. MATERIAL AND METHODS According to Youden's index, active disease patients were divided into high and low lncRNA NKILA groups. RESULTS Patients in the high lncRNA NKILA level group had significantly longer length of treatment and higher re-hospitalization rate at 3 years after discharge. Plasma levels of TGF-ß1 were also higher in active ankylosing spondylitis patients than in healthy controls. Levels of plasma lncRNA NKILA and TGF-ß1 were significantly and positively correlated in ankylosing spondylitis patients but not in healthy controls. CONCLUSIONS Overexpression of lncRNA NKILA in ankylosing spondylitis is correlated with active disease and predicts length of treatment. LncRNA NKILA may participate in ankylosing spondylitis through the interaction with TGF-ß1, which is a key player in this disease.