Because fibromyalgia (FM) is often comorbid with anxiety, and monoamine oxidase A (MAOA) was reported to be associated with anxiety, we determine if there is MAOA gene polymorphism associated with FM patients. Moreover, interleukin 4 (IL-4) was found to be an important cytokine participating in the immunologic pathway of T-helper 2 (Th-2) cells, in this study, we search if the genetic polymorphism of IL-4 intron3 could be demonstrated in FM patients. The genotype of sixty-two FM patients was compared with that of control subjects. The polymorphism of IL-4 intron3 variable number of tandem repeats (VNTR) was demonstrated by performing the genomic polymerase chain reaction (PCR) and analyzing the length of PCR product. Furthermore, the MAOA 941 G to T polymorphism was also determined by PCR-RFLP (restriction fragment length polymorphism) analysis. The MAOA 941 position genotype polymorphism between FM and control subjects was found neither statistically different in male (p=0.60) or female (p=0.52), nor total allelic frequency (p=0.52). Similarly, the difference of IL-4 intron3 polymorphism between FM and control was neither existing in genotype (p=0.06), nor allele frequency (p=0.07). The result suggests either the genetic linkage between FM and anxiety or that between FM and immunologic diseases are weak. Accordingly, the MAOA 941 position and IL-4 intron3 polymorphisms are not susceptible markers to predict FM.