The present study was designed to assess the relationship between puerperal hormonal changes and mood. Twenty-five postpartum physically and mentally healthy, drug-free women were included in the study; seven later dropped out. Blood samples 'were drawn between 8 and 9 a.m. just prior to delivery, and again three days after delivery, before discharge. Blood levels of LH TSH, FSH, estrogen and prolactin were determined. Three days after delivery, a psychiatric interview was conducted during which psychometric rating scales (Brief Psychiatric Rating Scale, Hamilton Depression and Hamilton Anxiety Rating Scales, and Beck Depression Inventory) were completed. The rate of change in hormonal blood levels was analyzed in relation to the scores on the rating scales. Results showed that the rise in prolactin plasma levels had a negative and significant correlation with the scores on the Hamilton anxiety scale. This may indicate that high prolactin plasma levels, associated with milk production, may lead to lower anxiety levels in lactating women.