He had advocated a dress code for women, saying skimpy attire invites sexual assault.
As his statement evoked strong protests from civil society groups and disapproval from Chief Minister DV Sadananda Gowda, Patil fell back on the usual explanation -- that he had been misquoted.
Patil and Laxman Savadi, who has quit as cooperation and agricultural marketing minister, were caught watching a porn clip in the assembly Tuesday on the cellphone of J Krishna Palemar, who has stepped down as environment and ports minister.
The three resignations Wednesday have taken to four the number of BJP ministers to lose office over sex related issues.
Haratalu Halappa quit as food and civil supplies minister in 2010 after he was accused of raping his friend's wife.
BJP legislator M.P. Renukacharya, now the excise minister, has been accused by a nurse, Jayalakshmi, of sexually harassing her.