The number of gonorrhoea and syphilis infections has fallen, latest figures for the UK show, although diagnoses of genital warts and herpes are up.
Statistics from the Health Protection Agency (HPA) showed the number of new gonorrhoea infections was the lowest in nearly a decade.
Overall sexually transmitted infections were up last year by 0.5%, mostly due to the increase in herpes and warts.
Those aged between 16 to 24 are still disproportionately affected by STIs.
While just 12% of the UK population falls into this age group, they account for more than half of all new STIs diagnosed in the UK.
They saw 65% of new diagnoses of chlamydia, which remains the most common STI - with a total of 123,018 cases.
However the rise in the number of infections with this disease, which can cause infertility if not treated, has slowed markedly.
The HPA suggested the significant rise in the number of herpes and warps diagnoses was probably down to the the greater use of more sensitive tests.
The drop in gonorrhoea cases meanwhile took place against a backdrop of increased screening, the HPA said, and as such showed the success of local intervention policies of targeting this condition as well as syphilis.
"These are both infections which tend to be geographically clustered and concentrated in specific population core groups, such as black ethnic minorities and men who have sex with men," Dr Gwenda Hughes, head of the HPA sexually transmitted infections department, said.
"Effective local interventions may therefore have had a significant influence on transmission and frequency of these infections so this decrease can be seen as testament to the hard work of health professionals and colleagues in the NHS.
She added: "We need to continue to encourage safer sex, including condom use, to help reduce the spread of STIs.
"We also recommend that anyone with a new or casual sexual partner gets tested regularly at a genito-urinary medicine clinic or through the National Chlamydia Screening Programme."
To coincide with the publication of the latest figures, Unicef and the Terrence Higgins Trust (THT) have released a study looking at young people's attitudes to sexual health.
It found fear of pregnancy was a much greater concern for young people than STIs, which means they may stop using condoms once they start using the most effective forms of contraception.
It urged the creation of a "one-stop information service" for teenagers and better training for those teaching Sex and Relationship classes in schools.
David Bull, UNICEF UK's chief executive, said: "While we recognise the government's increased spending to improve the sexual health of young people in the UK, it's clear from our research that young people themselves want and need better access to the information and services that will help them prevent STIs.
"UNICEF knows from global experiences that youth-friendly information and services are key in the prevention of STIs."
Brook, which provides young people with advice about sexual health, welcomed the figures.
"It is excellent news that the increase in diagnoses of STIs is slowing down," said director Simon Blake.
"The HPA's findings show that we must continue to support young people to make good decisions that protect their physical and emotional health.
"High quality education and services need to be relevant to people's everyday experience of sex and relationships. Messages about unwanted pregnancy and STIs must be relevant and in context of young people's lives."