This study focuses on the causes and consequences of delay in diagnosis of ankylosing spondylitis (AS). Seventy consecutive patients presenting at a rheumatology clinic in India were studied. Mean (+/-S.D) delay in diagnosis was 6.9 (+/-5.2) years. The main cause of delay was incorrect diagnosis as non-specific back pain (19/54, 35.1%), degenerative disc disease (14/54, 25.9%), rheumatoid arthritis (11/54, 20.37%), and tuberculosis of spine (9/54, 16.6%) in that order, for which the patient received prolonged treatment. Absence of extra-articular manifestations and juvenile age also significantly correlated with diagnostic delay. Delay in diagnosis resulted in significantly worse disease activity index (BASDAI), functional index (BASFI), and damage index (BASMI). Most incorrect initial diagnoses were made by orthopedicians (75.9%), followed by general physician (50%), and rheumatologist (12%). Continuing medical education workshops with a focus on clinical diagnosis of inflammatory back pain may help in early diagnosis of AS.