Abstract: The invention relates to a method and an arrangement for terminal-oriented performance monitoring in a telecommunications network having a public side and a mobile subscriber side with terminals. Information with respect to network performance is collected by the subscriber terminals or in connection with the subscriber terminals and transferred to the public side. The information includes the grade of service, information on error conditions and information on the quality of the transmission channel in the network and non-connection information. With the aid of the invention the network operator is provided with a picture of the performance from the point of view of the customer and he can thus operate the network more effectively at the same time as the performance experienced by the customer is kept under control.