The electromagnetic problem has been solved for randomly oriented nonspherical and inhomogeneous structures with complex refractive indices 1.40175-2.93 x 10(-5)i (oxygenated hemoglobin) and 1.33018-2.09 x 10(-8)i (immersed in water) due to the T-matrix method. The light scattering properties of spheroidal erythrocytes for each condition were obtained using so-called Mie theory. In this study, the spheroidal erythrocyte is assumed to have a radius of 2.78 mu m, giving it a volume equivalent to the average actual erythrocyte, and is illuminated by a plane wave of lambda = 873 nm. The T-matrix elements are obtained by numerical integration in each condition. Comparisons for erythrocytes with oxygenated hemoglobin and immersed in water, and its results for large, randomly oriented spheroids, show that the applicability range of the scattering process depends on the imaginary part of the refractive index and is changed for different elements of the scattering matrix. (c) 2005 Elsevier Ltd. All rights reserved.