We evaluated magnetic resonance imaging (MRI) changes in ankylosing spondylitis (AS) patients with longstanding disease and investigated whether there is any relationship between MRI findings and validated methods of disease assessment. A total of 34 AS patients with disease duration greater than 10 years were included in this observational cross-sectional study (26 men, 8 women). The main outcome measures were Bath Ankylosing Spondylitis Functional Index (BASFI), Bath Ankylosing Spondylitis Disease Activity Index (BASDAI), Bath Ankylosing Spondylitis Global assessment (BASG), Bath Ankylosing Spondylitis Metrology Index (BASMI), MRI of the thoracic and lumbar spine (AS spi MRI A) and measurement of serum erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), plasma viscosity (PV) and immunoglobulin A (Ig A). The median scores for the acute lesions based on AS spi MRI A scoring system was 2.5 (0-4.12). The respective mean ESR and CRP were 36 (SD, 24.00) mm/h and 14.19 (SD, 24.00) mg/l with the median PV of 1.8 (1.75-1.87). The median BASG, BASFI and BASDAI were 4.55 (2.37-5.55), 4.40(2.31-5.47) and 4.32 (3.07-6.48), respectively. No significant correlations were found between the acute MRI scores and each of the clinical instruments and laboratory markers of inflammation. In this study, majority of AS patients with longstanding disease had very low AS spi MRI A scores or no evidence of spinal inflammatory lesions. Our study would suggest that MRI should be used along with other measures of disease activity in the assessment of symptomatic AS patients with longstanding disease.