The aim of this paper was to test the possibility of implementation of the commercial-off-the-shelf (COTS) quasi-low-dropout voltage regulator in a harsh bremsstrahlung environment (in the case of a lifelong exposure to moderate total ionising doses). Results of examination of the LT1086CT5 voltage regulator, performed in the field of X-rays, are presented in this paper. Biased and loaded circuits demonstrated acceptable characteristics in the bremsstrahlung environment for total doses up to 433 Gy, but some samples of unbiased circuits demonstrated unacceptable decline of the output voltage even after absorption of ionising dose of 260 Gy. One-week room temperature annealing led to a further degradation of all of the irradiated voltage regulators, both unbiased and biased, during irradiation. All the examined samples remained functional, but pointed to numerous limitations for implementation of these COTS voltage regulators in an ionising radiation environment.