We conducted the present study to determine the incidence of disease flares (relapses and recurrences) in a series of patients with biopsy-proven giant cell arteritis (GCA). We assessed a series of 174 patients who were diagnosed with biopsy-proven GCA, uniformly treated, and followed at the rheumatology division of Hospital Xeral-Calde (Lugo, Spain), the single rheumatology division for a well-defined population. All of them were followed for at least 1 year after the disease diagnosis. Seventy-one (40.8%) experienced relapses or recurrences of the disease. Patients who had relapses or recurrences did not show clinical differences when compared with the remaining biopsy-proven GCA patients. However, the total duration of corticosteroid therapy was significantly longer in those patients who had relapses or recurrences of the disease. The median dose of prednisone and the median duration of corticosteroid treatment at the time of the first relapse were 5 mg/d and 16 months, respectively. Headache (52%) was the most common feature at the time of the first relapse. Polymyalgia rheumatica manifestations occurred in 30% of the patients at that time. However, none of them developed visual loss. Thirty-two patients experienced recurrences of the disease when prednisone dose had been discontinued. The median time from the disease diagnosis to the time of the recurrence was 23 months. The presence of anemia (hemoglobin <12 g/dL) at the time of disease diagnosis was the best predictor of relapses or recurrences of GCA (odds ratio, 2.17; 95% confidence interval, 1.02-4.62; p = 0.04). The results from the present study confirm that relapses and recurrences are frequent in homogenously treated patients with biopsy-proven GCA. A chronic inflammatory response manifested by anemia at the time of disease diagnosis may predict the development of disease flares.