We present a review of the progress in the field of 2DEG in strained Si/SiGe heterostructures during the past 20 or so years. We highlight the difference in the key challenges in sample preparation between the samples for low-temperature transport studies and those for field-effect transistor (FET) applications. The requirements of low electron density and high electron mobility for low-temperature electron transport are also discussed. High mobility (> 300,000 cm(2)/V S) can be reproducibly achieved recently and low electron sheet density (1.1 x 1011 cm(-2)) in modulation-doped samples (as opposed to gated) has also been observed. Magnetotransport measurements provide indications of the mobility limiting factors thereby pointing to the plausible directions for further improvements on the strained Si sample quality. (c) 2008 Elsevier B.V. All rights reserved.