It has emerged the HSE spends around €70,000 a day on taxis, one of the highest users in western Europe.
The Sunday Independent reports that one cab company received almost €1m last year from the Executive.
The revelations will increase pressure on the HSE to find more cost effective solutions for transporting patients and specimens.
The figures, which were obtained through a freedom of Information request show that two Dublin firms netted almost €1m last year and a third firm made over €600,000.
In Cork a firm made €755,000 with six other firms making earnings of €200,000-€390,000.