This is a cross-sectional study to assess the prevalence and causes of anemia in the primary Sjögren's syndrome (pSS). One hundred and thirty-two consecutive patients with pSS were enrolled into the study. Standard hematological and immunological tests and examination of bone marrow were performed. Anemia occurred in 45 (34.1%) patients. The causes of anemia included anemia of chronic disease (69%), autoimmune hemolytic anemia (AIHA, 18%), iron deficiency anemia (9%) and other causes (4%), of which AIHA caused the most severe anemia. The prevalence of ANA, anti-Ro/SSA, and anti-La/SSB was much higher in patients with anemia than those without anemia. Anticardiolipin antibodies were most commonly detected in AIHA; the prevalence of IgG and hypocomplementemia in AIHA was much higher in patients without anemia. Abnormal bone marrow changes were observed in two cases with anemia, one with morphological changes in the myeloid, megakaryocytic, and erythroid lineages and one with hypocellularity in the erythroid lineage. Therefore, pSS patients with anemia may be associated with destruction of peripheral mature blood cells, impaired red cells production, and hematopoietic abnormalities due to an immune mechanism, although the concrete pathogenesis is still unclear.