Lead Australian researcher and renowned sex therapist Dr Rosie King found the results "exciting".
"We found 38 per cent of mature men and 29 per cent of mature women were having sex more than once a week," The Daily Telegraph quoted King, as saying.
"That's a significant amount of older men and women having a lot of sex, perhaps more than many of us suspected.
"These people are not frothy young singles out at the clubs having hot casual sex.
"They're more likely to be at home with their loved one in front of the fire. So, in that respect it's quite impressive," she added.
However, a quarter of the men admitted that they regularly suffered from premature ejaculation and erectile difficulties.
King said issues with sexual function increased with age, as more men developed diabetes and obesity, and started taking medication known to affect performance.
Also a quarter of women said that they have trouble reaching orgasm and a third admitting to a lack of sexual interest.
"For a lot of these women, their sex drive isn't like what they see on Sex and the City or read about in romance novels so they think there's something wrong with them, when it's totally normal," she said.