New York City- A Madison Ave. surgeon left a patient virtually impotent after operating to lengthen his manhood, a lawsuit claims.

Eric Neuberger, 31, contends his pre-op libido let him “engage in intercourse approximately 30 to 50 times a month.”

But his sexual appetite was destroyed by Dr. Rodney Barron’s work, Neuberger said.

Neuberger, a musician from Middletown, Orange County, paid $6,600 to The Barron Centers Medical Associates, which has offices on Madison Ave. and in Beverly Hills.

“It was more a confidence thing than a physical thing,” he said in the lawsuit, filed in Manhattan Supreme Court.

“[My girlfriend said] that I didn’t need to have it done, there was nothing wrong with me. I thought it would improve my confidence.

“[Barron] said the worst-case scenario was that I would have to come back for a followup surgery.”

But Neuberger said he now manages to have sex only once a month and suffers from scarring and pain.

And he said he was not warned of the risks before the surgery, described by his lawyers as “unproved, unsafe, ineffective and experimental.”

He is claiming unspecified damages for mental anguish that he argues forced him to drop out of school and somehow hurt his musical ability.

Barron countered in court papers that “Mr. Neuberger had injured himself during sex.”

A trial date has yet to be set.