The first part of this paper is a review of the technique known variously as laser speckle contrast imaging (LSCI), laser speckle imaging (LSI), or laser speckle contrast analysis (LASCA). The technique uses the phenomenon of laser speckle. The basic theory of laser speckle was developed in the 1960s.1 In the 1970s, time-varying speckle, caused by motion, became a subject for research. In particular, a connection was established between the fluctuations of the speckle pattern and the movement of scattering centers in living organisms, for example, the movement of red blood cells.2 One way in which the speckle fluctuations manifest themselves is in a reduction in the normally high contrast of the speckle pattern. In the 1980s, this effect was used in a photographic technique known as single-exposure speckle photography, developed to study blood flow in the retina.3 Although the method worked, the need to process the photographs before the information could be accessed proved to be a major problem and interest in the technique waned. In the 1990s, new digital methods allowed the development of a real-time version of the method4 and this has proved to be much more useful. There are, however, some problems, both theoretical and practical, and the second part of the paper will attempt to address these.