To assess the long-term safety and tolerability of ACP-103 in subjects with Parkinson's disease psychosis.

This study did not have a fixed duration, and the duration of individual subject participation was determined based on investigator assessment of subject tolerability and continued benefit until such time as either the drug was commercially available in the US, or an alternate treatment extension was available in non-US regions. For this reason, no subjects, therefore, were considered to have "completed" the study.

Inclusion Criteria:

• Subject has completed the treatment period of a previous blinded study of pimavanserin
• The subject is willing and able to provide consent
• Caregiver is willing and able to accompany the subject to all visits

Exclusion Criteria:

• Subject has current evidence of a serious and or unstable cardiovascular, respiratory, gastrointestinal, renal, hematologic or other medical disorder
• Subject is judged by the Investigator to be inappropriate for the study