Optical properties of suspensions of contractile models, myofibrils and two actomyosins ("natural" and "synthetic"), have been investigated. The turbidity and the wavelength exponent of suspensions of the original, contracted, and aggregated models have been measured at different concentrations, light wavelengths, and solid angles of the spectrophotometer photocell. Change in the turbidity of these suspensions upon addition of MgATP is compared to changes in the particle size and gel phase volume of suspensions. The turbidity of myofibril and actomyosin suspensions is shown to be strongly dependent on the conditions of its measurement. The extent of turbidity changes upon the contraction of myofibrils and superprecipitation of actomyosin also depends on measurement conditions and is proportional to the difference between the densities of the original and contracted particles. It is suggested that the increase in suspension turbidity upon addition of MgATP is due to changes in the form of the light-scattering angular diagram rather than to the enhancement of total light scattering of suspensions.