[en] Metal-Oxide-semiconductor (MOS) dosimeters are MOS transistors with a specially processed gate insulator in order to make it radiation soft. They are gaining an increasing interest because of their numerous advantages with respect to more conventional dosimeters such as TLDs: low cost, small size and weight, robustness, accuracy, large measurable dose range, sensitivity to low energy (< 10 keV) radiation, real-time or delayed direct read-out, information retention, possibility of monolithic integration with other sensors and/or circuitry capable of realizing measurement, signal conditioning and data processing, possibility of use without power supply. Furthermore the behaviour of the MOS transistor is now basically known. Consequently they are a very attractive solution in several application fields such as space, nuclear plants, military, emergency dosimetry, medical, equipment calibration and control. Furthermore recent results allow application in the 10 μGy range to personnel dosimetry. We have developed a special technological process leading to a MOS transistor with a very thick gate insulator (up to 3 μm) and large gate area (1.75 10^-3 cm² ), operating in the depletion mode, without using ion implantation to adjust the threshold voltage. This allows to obtain a high intrinsic radiation sensitivity (up to 0.5 V/Gy in the unbiased mode) for a single transistor together with a very small fading (8% after 1000 h at room temperature) and low noise (30 μV minimum measurable signal due to noise for a 1 MHz bandwidth). In this frame the aim of this paper is to present the basic principle, the main characteristics - radiation sensitivity, stability with time and temperature - and limitations of MOS dosimeters. Limitations have been particularly studied with respect to process variability - which has consequences on cost and measurement accuracy - and temperature control during read-out. The most recent results using several stacked MOS transistors coupled by the so-called 'body effect' will be developed. It will be shown that this configuration is attractive to measure very low doses (radiation sensitivity of several 10 V/Gy) but that a compromise has to be solved between radiation sensitivity, output voltage value and temperature sensitivity. Process variability will appear as a critical parameter with respect to dose measurement in the 10 μGy range. (author)