This essay describes and analyzes how the kimanakta-kimanagan, or a custom of lending-out/borrowing of livestock including cattle, among the Kipsigis people of Kenya has changed through the drastic acculturation they have consequtively experienced through out this century after they came into contact with the European settlers in the Kenyan “White Highland”. Moreover, this essay explains how the values of cattle have changed and survived in the Kipsigis society which is among so-called “East African cattle complex” societies, with the special reference to the kimanakta-kimanagan system. The Kipsigis have been generally regarded as a “model” East African people in that this traditionally pastoral people very successfully adapted themselves to the colonial and capitalistic economy by rapidly adopting maize cultivation with plough and by shifting from communal land tenure to private land tenure. As a result, it is claimed, they lessened their pastoral attributes in large and cattle, around which almost all the traditional values of the people had centred, descalated to a simple article of commerse which was even less valuable than maize. It may be true that some characteristics of the traditional Kipsigis culture centred around cattle declined, but it can not be denied that the kimanakta-kimanagan system survives well in the course of the acculturation and that cattle still maintain importance as multiple media through which social relations are structured. Traditionally, the kimanakta-kimanagan contract was made on individual base among age-mates, affines, relatives, clansmen etc., and a cow, she-goat, or ewe was sent out as long-termed loan so that it could supply milk and blood to drink to the debtor's family. This system contributed to reduce inequality in the number of livestock, which were the then primary means of survival, held by individuals as well as possible discontents among the people, and therefore to maintain the unity of the acephalous and non-segmental Kipsigis society. Researchers are apt to underestimate, or even neglect, the significance of the existence of the highly transformed modern kimanakta-kimanagan system, judging form the descalation of the relative economic value of cattle. The system has been flexibly amended and developing new variations of practice in accordance with the needs derived from the modernization. But thus, all the more, it makes for minimizing the inequality not only in cattle holdings but also in their economy as a whole in the modern Kipsigis society. This may be the very reason the system survives the radical changes of their life style. In other words, it achieved its involution in this way.