The number of reported sexually transmitted diseases (STDs) has dropped by 4% in the past year across Dacorum.
The figures, released by Public Health England show a fall in the number of cases from 1,462 to 1,398.
In total, 808 cases of chlamydia were reported across the borough, compared to 891 last year.
Of these, 705 were in the 15-24 age group and 92 were in the over-25 group.
The number of reported cases of gonorrhoea also fell from 28 in 2012 to 18 in 2013,
The figures also show a 18% drop in the number of cases of herpes – down from 71 to 58.
There was one more reported case of syphilis (up from one to two) and nine fewer cases of genital warts (down from 190 to 181) compared to last year.
Nationally, there was a slight fall in the number of STDs diagnosed in England - 446,253 this year compared to 448,775 the previous year.
Chlamydia was the most common STI, making up 47% of all diagnoses (208,755), while gonorrhoea diagnoses saw a large rise, up 15% from 2012 to 2013 (29,291).
Dr Catherine Lowndes, consultant scientist in PHE’s STI surveillance team said: “Chlamydia can have serious consequences, including infertility, if it’s not treated.
“This data shows we need to do more to encourage young adults to ask for testing every year when they attend health services.”