We investigate some basic properties of three-dimensional nonsteady compressible magnetohydrodynamic (MHD) perturbations in a polytropic radial MHD wind with spherical symmetry. At a large radial distance r, we derive analytical solutions for MHD slow- and fast-type perturbations for several rational values of the polytropic index &ggr;. The propagation characteristics of MHD slow-type perturbations, which are more magnetic at large r, are very similar to those of Alfv¿nic perturbations; namely, there exists the same characteristic frequency fc for both types of perturbations, and the transverse magnetic field perturbation associated with MHD slow-type perturbations also tends to dominate the background radial magnetic field at large r except in the zero frequency limit. The propagation characteristics of MHD fast-type perturbations, which are more acoustic at large r, depend upon the value of &ggr; because the sound speed CS in the wind scales as ~r-(&ggr;-1) at large r. For the typical case of &ggr;2, acoustic perturbations actually become MHD slow perturbations at large r because CS is now slower than the Alfv¿n speed CA, which scales as ~r-1 at large r, and these acoustic perturbations do not propagate relative to the wind, yet the wind advects them radially outward. For the special case of &ggr;=2, there exists another characteristic frequency fa. For perturbation frequency f>fa, acoustic perturbations propagate relative to the wind, whereas for f<fa, they appear standing relative to the wind. We discuss the relevance of these results, both MHD fast- and slow-type perturbations with &ggr;<2, to interplanetary fluctuations in the inner solar wind. In particular, we interpret the increasing trends with r of the relative density and magnetic field fluctuations observed in high-speed solar winds within 0.3 to 1 AU as manifestation of MHD fast- and slow-type perturbations. ¿ American Geophysical Union 1993