This study reports the simple synthesis of MFe2O4 (where M = Cu, Ni, and Zn) nanoparticles by a modified sol-gel method using high purity metal nitrates and aloe vera plant extracted solution. Using of aloe vera extract simplifies the process and provides an alternative process for a simple and economical synthesis of nanocrystalline ferrites. The obtained precursors were characterized by TG/DTA to determine the thermal decomposition and subsequently were cc at different temperatures in the range of 600-900 degrees C for 2 h to obtain the ferrite nanoparticles. The calcined samples were characterized by XRD, FT-IR, SEM, and TEM. All the prepared samples are polycrystalline and have spinel structure with crystallite sizes of 15-70 nm. The crystallite size increases with increasing the calcination temperature. Magnetic properties of the prepared ferrite samples were measured using Vibrating sample magnetometer (VSM). The room temperature magnetic behavior of as-prepared ferrite powders can be explained as the results of the three important factors: impurity phase of a-Fe2O3, cationic distribution in spinel structure, and the surface spin structure of nanoparticles. (C) 2010 Elsevier B.V. All rights reserved.