Аннотация:Some types of nonlinear ordinary differential equations (homogeneous, generalized homogeneous, autonomous) are analyzed. They may be obtained from the nonlinear equations in partial derivatives as the result of applying the known methods (such as method of introducing self-similar variables, method of separation of variables, methods of group analysis). The subsequent study is carried out using special substitutions, which reduce the order of ordinary differential equation. A great number of examples of solving nonlinear ordinary differential equations has been developed. Using the suggested substitutions, their exact analytical solutions have been devised. The examples of nonlinear equations (including differential equations of heat and mass transfer, filtration, equation of freely spreading of the plastic layer on a plane) have been introduced.