Production planning is the main aspect for a manufacturer affecting an income of a company. Correct production planning policy, chosen for the right product at the right moment in the product life cycle (PLC), lessens production, storing and other related costs. This arises such problems to be solved as defining the present a PLC phase of a product as also determining a transition point - a moment of time (period), when the PLC phase is changed. The paper presents the Agents Based Data Mining and Decision Support system, meant for supporting a production manager in his/her produc¬tion planning decisions. The developed system is based on the analysis of historical demand for products and on the information about transi¬tions between phases in life cycles of those products. The architecture of the developed system is presented as also an analysis of testing on the real-world data results is given.