The National Health Laboratory Service as the preferred pathology service provider for the public health sector in South Africa, developed a national laboratory handbook to improve the clinic-laboratory-interface. A separate primary health care laboratory handbook was developed as part of the ideal clinic initiative by the National Department of Health. This study aimed to assess adherence to these guidelines using CD4 rejections the indicator. The retrospective crosssectional study design was used to analyse national laboratory data for the period from January to December 2019. Data were analysed using SAS 9.4. Lookup tables assigned the origin (health facility/laboratory), rejection reason, and sub-reason based on the populated rejection description that was captured in the laboratory information system. The rejection rate [RR = (rejections/total volume) ´ 100] was reported at the national, provincial and district levels. There were 85,378 rejections reported for 2,844,242 tests (RR 3.0%). Data was reported for 4136 health facilities across nine provinces. The RR was higher for an origin defined as health facility (2.9%) than laboratories (0.1%). The most common rejection reason was unsuitable specimen received (RR=2.3%), representing 75% of all rejections. This rejection criteria included using the incorrect anticoagulant, clotted sample and haemolysis. The provincial RR ranged from 2.2% to 4.0%. Three districts had an elevated RR ≥6% (organisational cut-off set at RR ≤5%). This study demonstrated the value of laboratory data to assess specimen rejections and identify causes to facilitate targeted training.