  We investigate the large scale matter distribution adopting QSOs as matter
tracer. The quasar catalogue based on the SDSS DR7 is used. The void finding
algorithm is presented and statistical properties of void sizes and shapes are
determined. Number of large voids in the quasar distribution is greater than
the number of the same size voids found in the random distribution. The largest
voids with diameters exceeding 300 Mpc indicate an existence of comparable size
areas of lower than the average matter density. No void-void space correlations
have been detected, and no larger scale deviations from the uniform
distribution are revealed. The average CMB temperature in the directions of the
largest voids is lower than in the surrounding areas by 0.0046 +/- 0.0028 mK.
This figure is compared to the amplitude of the expected temperature depletion
caused by the Integrated Sachs-Wolfe effect.
