Gilead is the largest maker of HIV/AIDS drugs globally and pre-tax profits at its main Irish unit, Gilead Science, decreased from $16.5m to $14.9m in the 12 months to the end of December 2012.
The company employs 240 people in Ireland and the firm's Cork operation is the company's main international distribution operation.
The figures show that revenues at the Irish unit last year increased by 5.5pc from $2.9bn to $3bn.
The $3bn in sales recorded at the Irish unit account for 31pc of Gilead's global revenues of $9.7bn last year. The directors' report states that "sales growth for the year is primarily due to an increase in the volume of sales of HIV products".
Gilead's Irish arm is mainly involved in manufacturing, quality control, packaging, and the release and distribution of the company's products in the EU and other international locations.
Gilead's blockbuster HIV drug Altripla last year generated sales of $3.57bn and is manufactured in Cork.
Altripla provides a combination of three medicines to HIV/AIDS patients in a single daily pill.