The main objective of this paper is to measure the relationships between the ecotypes belonging to the Tigai and Tsurcana breeds of Romania and to quantify the genetic diversity within them from the informational statistics point of view, depending on the relief forms of the biotope in which they live, using the genetic variants of some selective genetic markers. The researches were carried out on ecotypes of the most ubiquitous sheep breeds in Romania, Tsigai and Tsurcana whose biotopes are circumscribed by more relief forms: plain, hilly, sub-mountainous and mountainous. The sheep were electrophoretically typified at the determinant loci of haemoglobin and transferrin. Using the allelic frequencies of the haemoglobin and transferrin systems that have been processed by concepts of informational statistics, the differentiation / similarity degree among ecotypes within the two breeds was quantified by the genetic distance (D) and the informational correlation coefficient (Rx,y), as well as the diversity level (d) of the genetic structures of these ecotypes on the basis of informational energy (e). Also, the heterozygosity degree (Ht) at the Hb and Tf loci was calculated in relation to the genetic diversity level. The paper analyzes the causes of genetic similarities and differentiations among the ecotypes of these two breeds at the level of the two biochemical-genetic loci: allelic distribution of haemoglobin and transferrin, altitude of relief forms, habitat conditions etc. The benefits of such studies are also presented for the improvement, breeding and conservation of the ecotypes of these two sheep breeds from Romania.