Among images that leave little to the imagination are a man having sex with a goat, a transsexual posing and a naked woman straddling a supine Roman god.
"There is nothing here that you would not see on Facebook or daytime television," said Antonio Manfredi, director of the Contemporary Art Museum (CAM) in Casoria near Naples and himself a model in one work.
"Even today when we talk about erotic works, it is difficult to show them. But as a politically incorrect museum, we thought that it was really interesting."
Manfredi said the culture ministry had attempted to "censor" the exhibition by initially giving the artists permission to photograph the ancient frescoes but then withdrawing approval when their intent became clear.
The museum said in a statement that the idea behind the exhibit was to "transfer these works into the present".
The CAM in Casoria, which has attracted controversy before by publicly burning works from its collection in protest against the government, receives
no public funds and survives on donations and ticket sales.
"Since I regard myself to be a strong woman, I said this is my picture, I want to make this, and I'm proud of myself," said artist Veronika Bayer from Austria, standing in front of a sexually graphic image of herself on a marble bas-relief sculpture.
"It's very aesthetic. It's not cheap pornography, although you see everything. But yes, it's a kind of a statement for me," she said.
Mimmo Femiano, an Italian man visiting the exhibition, said he did not consider it pornography.
"Pornography is abnormal while eroticism, on the contrary, is art," he said. "I am surprised this show was censored because I see nothing abnormal or special."