NSW has recorded its lowest quarterly number of HIV cases but health authorities remain concerned because testing rates have also declined.

Chief Health Officer Kerry Chant is urging anyone at risk to get tested, particularly if it has been more than a year since their last test.

"I strongly encourage people who are at risk to please get tested or do a test at home," Dr Chant said on Wednesday.

"Early testing, diagnosis and treatment prevent transmission."

In the first quarter of this year, 30 NSW residents were diagnosed with HIV - a 54 per cent drop compared with the first-quarter average for the past five years.

"However, while this drop is welcome, we note that testing rates have also declined," Dr Chant said.

HIV testing was 10 per cent lower in the first quarter of this year, compared with the first quarter of 2021, and 11 per cent lower than the first quarter of 2020.

People can get tested at their GP, sexual health service, or use an at-home self-testing kit

The NSW HIV Strategy 2021-2025 aims for a 90 per cent reduction in the rate of preventable HIV infections to achieve the virtual elimination of HIV transmission in the state.

In Australia, people at the highest risk of getting HIV infection are: men who have sex with men, people who have sex with people from countries with a high rate of HIV infection, people who inject drugs, people who get tattoos or other piercings overseas and people who have sex with a person with a high risk of HIV.