Objectives: The aim of the study is to identify and compare prevalence of fibromyalgia (FM) in axial spondyloarthritis (axSpA) patients according to American College of Rheumatology (ACR) 1990 FM, ACR 2010 FM classification and diagnosis and (ACTTION - American Pain Society Pain Taxonomy) AAPT 2018 FM diagnosis criteria. The second aim of study is to investigate the effect of FM on axSpA disease activity, quality of life, functionality and enthesopathy. Materials and Methods: The present study was single-center cross-sectional analysis conducted on 86 axSpA (61 nr-axSpA, 25 AS) patients according to the (Assessment in Spondyloarthritis International Society) ASAS criteria. Demographic characteristics, disease duration, HLA B27 positivity, erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), Bath AS Disease Activity Index (BASDAI), Bath AS Functional Index (BASFI), Bath Ankylosing Spondylitis Metrology Index (BASMI), Maastricht AS (Maastricht Ankylosing Spondylitis Enthesitis Score), AS Disease Activity Score-CRP (ASDAS-CRP), AS Disease Activity Score Sedimentation (ASDAS-ESR), Ankylosing Spondylitis Quality of Life (ASQoL) and Fibromyalgia Impact Questionnaire (FIQ) are measured. 1990 ACR and 2010 ACR FM classification, diagnosis criteria and AAPT 2018 FM diagnosis criteria were applied to all patients. Results: Seven (8.1%), 36 (41.9%), 33 (38.4%) of the patients were FM according to the 1990 ACR FM, 2010 ACR FM criteria and 2018 AAPT 2018 FM criteria, respectively. 1990 ACR FM criteria was correlated with BASFI (r=0.375, p=0.001), BASDAI (r=0.250, p=0.020), MASES (r=0.228, p=0.035), ASQol (r=0.264, p=0.014) and FIQ (r=0.321, p=0.003). 2010 ACR FM criteria was correlated with BASFI, BASMI, BASDAI, ASDAS-ESR, ASDAS-CRP, MASES, ASQoL and FIQ (r between: 0.267 and 0.666, p between: 0.001-0.013). AAPT 2018 FM criteria was correlated with BASDAI (r=0.282, p=0.008) and FIQ (r=0.263, p=0.014). Conclusions: The presence of FM negatively affects the quality of life, disease activity and functionality in axSpA patients. AAPT 2018 FM criteria practically may be used to define FM in daily practice. Concomitant FM in axSpA patients might be taken into consideration for the management of treatment.