The HSE is recalling all copies of a sex education DVD after a school reported "inappropriate content" on the resource.
The HSE said: "It has been reported to the HSE's Sexual Health and Crisis Pregnancy Programme that inappropriate content may have been copied by a third party onto a HSE sexual health education DVD resource."
The resource, called Busy Bodies, consists of a booklet and a DVD that is provided by the HSE to schools and parents.
It is aimed at 5th and 6th class students in primary schools.
The Busy Bodies Adolescent Development Programme provides information on the physical and emotional changes that children may experience during puberty.
On Thursday evening a primary school reported the incident to the HSE.
The HSE said that "the DVD was not viewed by children at any time, was removed from the school, and the HSE reported this incident to the Department of Education, and to the gardaí, who are now investigating".
Helen Deely, HSE programme lead for Sexual Health and Crisis Pregnancy, said: "We are concerned about this report, but following our initial investigation, this appears to be an isolated incident relating to one individual copy of the resource.
"As well as reporting this to the gardaí, we have commenced a comprehensive investigation into how this happened.
"As a precaution, the HSE is writing to all schools and recipients of the resource, asking that they be returned to schools by parents, and removed from use and circulation until the investigation is complete."
Ms Deely added: "If parents have any questions about this, they can contact the HSE live team Monday-Saturday, 8am-8pm, on 1850 24 1850 or email firstname.lastname@example.org."