Background The pregnancy associated hormone relaxin induces loosening of the pelvic ligaments in several species. This study was undertaken to evaluate whether pregnant women with symptom‐giving pelvic girdle relaxation had increased serum relaxin concentrations during pregnancy.Method Serum relaxin concentrations were measured in 38 pregnant women with symptom‐giving pelvic girdle relaxation at the time of diagnosis, in the 30th and 38th week of pregnancy as well as 2 and 6 months after delivery. Fourteen pregnant women without symptoms served as a control group. Relaxin concentrations were measured by a homologous enzyme linked immuno‐sorbent assay. All participants were clinically examined including tests for symptom‐giving pelvic girdle relaxation.Results No differences in serum relaxin concentrations were found throughout pregnancy and after delivery between women with symptom‐giving pelvic girdle relaxation and positive clinical findings where compared to the control group. Moreover, there were no differences in serum relaxin concentrations in women with symptom‐giving pelvic girdle relaxation more than 2 months post partum when compared to women in whom the symptoms disappeared within two months after delivery.Conclusion The present results do not suggest an important role for relaxin in symptom‐giving pelvic girdle relaxation during human pregnancy.