Purpose: The study aimed to evaluate and compare the efficacy of TNF-α inhibitors in the treatment of ankylosing spondylitis in everyday medical practice. Materials and methods: We analysed the data of 106 patients with ankylosing spondylitis treated in 2012–2019 with TNF-α inhibitors (etanercept, adalimumab or golimumab) under the drug program of the National Health Fund. The observation period for each patient was 18 months. The disease activity was assessed at 3-month intervals on the basis of BASDAI (Bath Ankylosing Spondylitis Disease Activity Index) and ASDAS (Ankylosing Spondylitis Disease Activity Score). Results: The study covered 80 men and 26 women. The mean age of the patients was 37 years. The group receiving etanercept included 50 patients, adalimumab – 39 patients, and golimumab – 17 patients. Due to coexisting offaxial symptoms such as uveitis (n = 20/106) and peripheral arthritis (n = 39/106), some patients were simultaneously receiving classic disease-modifying antirheumatic drugs, i.e. methotrexate (n = 32/106), sulfasalazine (n = 8/106), cyclosporine (n = 5/106), and glucocorticosteroids (n = 14/106). All subgroups showed a significant clinical improvement in the form of a decrease in inflammatory markers and a decrease in disease activity after 3 months of treatment, increasing up to the 6th month. The biological drug was discontinued due to remission (according to BASDAI) in 20/48 patients taking etanercept and in 19/36 patients receiving adalimumab. The observation period following drug discontinuation for both groups was similar and lasted about 7 months. The remission time (according to BASDAI) without treatment was short; 3.55 ± 2.28 months for etanercept vs. 5.21 ± 2.53 months for adalimumab (p = 0.038). Conclusions: The inclusion of TNF-α inhibitors in patients with an unsatisfactory response to treatment with non-steroidal anti-inflammatory drugs resulted in a major reduction of disease activity. There was no statistically significant difference in treatment efficacy between individual TNF-α inhibitors, i.e. etanercept, adalimumab, and golimumab. The group treated with adalimumab was found with a trend towards longer-lasting remission after drug discontinuation, but it was short-lived and a return to treatment was necessary.