Effect of nonlinear thermal radiation on theunsteady magnetohydrodynamic slip flow of Casson fluid between parallel disks in the presence of thermophoresis and Brownian motion effects are investigated numerically. A similarity transformation is employed to reduce the governing partial differential equations into ordinary differential equations. Further, Runge- Kutta and Newton’s methods are adopted to solve the reduced ordinary differential equations. The effect of non-dimensional governing parameters, namely magnetic field parameter, Casson parameter, thermophoresis parameter, Brownian motion parameter, thermal radiation parameter, unsteadiness parameter, velocity slip parameter and temperature slip parameteron velocity, temperature and concentration fields are discussed and presented through graphs. Reduced Nusselt and Sherwood numbers are computed and presented through a table. It is found that rising values of nonlinear thermal radiation parameter depreciate the reduced Nusselt and Sherwood numbers. Thermophoresis and Brownian motion parameters have tendency to regulate the thermal and concentration boundary layers. Rising values of Casson parameter enhances the heat and mass transfer rate. © 2017, Shahid Rajaee Teacher Tarining University (SRTTU). All rights reserved.