A computer implemented system and method for pro-active application monitoring and alerting using affinity band. To enable pro-active monitoring, the present invention may derive affinity band. The invention accesses performance data generated from monitoring an application associated with one or more transaction and configuring iteration period to derive affinity band. The method provides configuring an interval within iteration period whereby all performance metric values may be aggregated and deriving affinity band for each of the performance metrics. The affinity band may then be used as benchmark or threshold to monitor current values for each of the performance metrics. Alerts may be raised through pro-active monitoring mechanism when the current values of the performance metric go beyond the threshold set, displaying a tendency to rise or go beyond normal values with extent of deviation.