This a Phase 4 non-treatment, long-term follow-up study of subjects who received AA4500 in a 12-month double blind placebo-controlled study (AUX CC 803 or AUX-CC-804) or in a 9-month open label study (AUX-CC-802 or AUX-CC-806) sponsored by Auxilium Pharmaceuticals, Inc. After participation in one of the aforementioned studies, subjects will be followed yearly for up to 4 consecutive long-term follow-up visits with at least 6 months between consecutive visits

At each long-term follow-up visit, subjects will be assessed for adverse events relative to their previous long-term follow-up assessment. Blood samples for the determination of antibodies to AUX-I and AUX-II and neutralizing antibodies to AUX-I and AUX-II will be collected at each long-term follow-up visit.

At each long-term follow-up visit, a flaccid penile examination will be performed and a curvature deformity measurement (with the penis in the erect state) will be recorded. Subjects will also be asked to complete the Peyronie's Disease Questionnaire (PDQ) and the International Index of Erectile Function (IIEF) questionnaire. At each visit, medical, surgical, or other treatments for Peyronie's disease since the last assessment will also be collected and recorded.

Inclusion Criteria:

1. Have received at least one injection of AA4500 and completed at least the first or last follow-up visit in one of the Auxilium-sponsored studies (AUX CC-802, AUX-CC-803, AUX-CC-804, or AUX-CC-806).

2. Be able and willing to comply with the follow-up assessments outlined in the protocol, as determined by the investigator.

3. Voluntarily sign and date an informed consent agreement approved by the Institutional Review Board/Independent Ethics Committee (IRB/IEC).

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   Exclusion Criteria:

   None

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Up to 750 subjects who received AA4500 and completed at least the first or last follow-up visit in one of the Auxilium-sponsored studies (AUX-CC-802, AUX-CC-803, AUX-CC-804, or AUX-CC-806).