• Safety - Adverse event frequency, vital signs (change from Baseline to Month 2) [ Time Frame: 60 days ] [ Designated as safety issue: Yes ]
  
• Tolerability - Proportion of participants who complete the trial [ Time Frame: 60 days ] [ Designated as safety issue: Yes ]
  

• Motor [ Time Frame: 60 days ] [ Designated as safety issue: No ]
  
• Cognition [ Time Frame: 60 days ] [ Designated as safety issue: No ]
  
• Behavior [ Time Frame: 60 days ] [ Designated as safety issue: No ]
  
• Serum estradiol levels - change from Baseline to Month 2 [ Time Frame: 60 days ] [ Designated as safety issue: No ]
  

POETRY is an 8-week study of 30 post-menopausal women with Parkinson's disease (PD) who will be enrolled at six clinical sites in the United States. The study is designed to measure the safety and tolerability of estrogen replacement therapy (ERT). The study will also measure how ERT affects thinking and behavior, movement and activities of daily living, as well as motor fluctuations and dyskinesias. Although we know there are gender differences in PD, no studies have assessed their impact on symptom management. Women with PD usually require less levodopa, are more likely to experience drug-related dyskinesia, and commonly report changes of their symptoms with menstruation, menopause and use of hormones, implying that hormonal changes may impact PD symptoms. All perimenopausal women face the decision whether or not to use estrogen replacement therapy (ERT) and for women with PD, information about estrogen's effects in PD may facilitate decision-making.

Inclusion Criteria:

• Post-menopausal women with Parkinson's disease who experience levodopa-related motor fluctuations averaging at least 2 hours daily in the "off" state confirmed by home diaries
• Must be on a stable dose of carbidopa/levodopa, immediate or controlled release therapy, antidepressants, or anxiolytics (for the last 30 days)

Exclusion Criteria:

• Insulin dependent diabetes
• Thyroid disease