Tukura, Bitrus WokheAudu, Stephen I.Abah, J.Inyanda, D.Ojile, J.O.Isah, J.Alao, B.2023-12-142023-12-142018-09-09.Kumar V, Abbas AK, Fausto N Robbins &Cotran pathologic Basis of Disease.ed.7th 2004 Saunders USA.Hund, E., Massart, D.L,andSmeyers-Verbeke, J. (2000). Inter-laboratory studies in analytical chemistry. AnalyticaChimicaActaVol 432. p. 145–657https://keffi.nsuk.edu.ng/handle/20.500.14448/5498Quality control (QC) is one of the most important impacts on laboratory testing—it ensures both precision and accuracy of patient sample results. The integrity of quality control samples is important to both management of overall quality as well as to meeting requirements of proficiency testing.The study was done to assess the quality control monitoring and evaluation of triglycerides & Cholesterol and also for interlaboratory studies of some haematological parameters[ White blood cell (WBC),Red blood cell (RBC)and Heamoglobin (Hgb), in Nisa Premier Hospital Abuja and the Benue State University Teaching Hospital Makurdi,North central Nigeria.The quality control monitoring& evaluation of Triglycerides and cholesterol were conducted for two consecutive months using the spectrophotometer(kenza240 TXbiolabo France),and the inter -laboratory studies was done in blood samples at both locations. At both locations determination was performed directly using the Automated Haematology Analyzer ((KX-21N Sysmex, USA)).The results of quality control showed that Trends (loss of reliability) and shifts (abrupt changes in the control mean) were noted in the results of this study, there were two major trends in July and more shifts in the month of August than in the month of July for triglycerides and a major trend and two violations of the Westgard Ruler for cholesterol.The results of inter-laboratory assessment of the haematological parameters shows that both imprecision and bias exist between both laboratories.Although imprecision values were generally in the range: 1< CVR <1.5, indicating ―Acceptable to marginal performance‖, the overall bias between laboratories was in the range: SDI >1.5 or SDI < -1.5; In this study, Warning signs were recorded but there was no cause for rejection of the analytical run. These violations typically identify smaller systematic error or analytical bias that is not often clinically significant or relevant.enQuality Control, Triglycerides, Cholesterol,Inter-laboratory,Westgard RuleArticle