Herdsmen-farmers’ conflicts have taken a calamitous dimension, which threatens the security, peaceful co-existence and national integration of Nigeria presently. This paper investigated the impact of herdsmen-farmers’ conflicts on national integration in Nigeria’s Fourth Republic. It adopted descriptive research method using secondary sources of data and frustration-aggression theory as the theoretical framework. The paper argued that there has once been peaceful relationship between herdsmen and farmers in Nigeria with few cases of minor misunderstandings but the conflict took a new dreadful wave due to certain factors such as climate change, population explosion, porosity of border, proliferation of arms, poverty, unemployment and the ineptitude action of government to these conflicts, among others. The paper argued that though some efforts have been made to address these clashes, such efforts appeared to be inadequate and thus achieved limited success. The paper further argued that persistent herdsmen-farmers’ conflict has now been threatening the peaceful co-existence and national integration of culturally segmented societies in Nigeria. The paper thus recommended, among others, that the government should formulate and implement proactive policies devoid of sentiments, bias and partisanship in curbing these conflicts. Government should demonstrate the political will in solving this problem by involving traditional rulers in the search for peace and harmony, using dialogue and Alternative Dispute Resolution (ADR) methods. Value re-orientation should be intensified through public enlightenment drive and the media so that Nigerians will appreciate the values that bind them together more than those that divide them and thus enhance tolerance of individual differences of other ethnic-nationalities towards national integration. Keywords: Farmers, Herdsmen, Herdsmen-farmer’s conflict, Impact, National integration..