The research problem – how to make the best economic diversification decision. It was analyzed in 12 cases – diversified farmer’s farm. It was found that the farm diversification decision was taken usually considering only one possible alternative solution. There was not carried out a complex farm diversification decision alternatives assessment analysis. Decision maker, subject only to those factors which it considered relevant, took the decision. Economy diversification decision was taken in haste. As a result, decision-makers have suffered many losses they had to make an additional investment, to study and to consult. This paper presents proposals to accept supposedly, best farm diversification decision.