Future work concerns packing RIPs with nanomaterials for targeting drugs and low release. Evaluation of Four Different Systems for Extraction of RNA from Stool Suspensions Using MS-2 Coliphage as an Exogenous Control for RT-PCR Inhibition Knowing when, and to what extent co-extracted inhibitors interfere with molecular RNA diagnostic assays is of utmost importance. The QIAamp Viral RNA Mini Kit (A); MagNA Pure LC2.0 Automatic extractor (B); KingFisher (C); and NucliSENS EasyMag (D) RNA extraction systems were evaluated for extraction efficiency and co-purification of inhibitors from stool suspensions. Real-Time Reverse Transcriptase Polymerase Chain Reaction (rRT-PCR) of MS-2 coliphage spiked into each system’s lysis buffer served as an external control for both. Cycle thresholds (Cts) of the MS2 were determined for RNA extracted from stool suspensions containing unknown (n = 93) or varying amounts of inhibitors (n = 92). Stool suspensions from the latter group were also used to determine whether MS-2 and enterovirus rRT-PCR inhibitions were correlated. Specifically 23 RNA extracts from stool suspensions were spiked with enterovirus RNA after extraction and 13 of these stool suspension were spiked with intact enterovirus before extraction. MS2 rRT-PCR inhibition varied for RNAs extracted by the different systems. Inhibition was noted in 12 (13.0%), 26 (28.3%), 7 (7.6%), and 7 (7.6%) of the first 93 RNA extracts, and 58 (63.0%), 55 (59.8%), 37 (40.2%) and 30 (32.6%) of the second 92 extracts for A, B, C, and D, respectively. Furthermore, enterovirus rRT-PCR inhibition correlated with MS2 rRT-PCR inhibition for added enterovirus RNA or virus particles. In conclusion, rRT-PCR for MS-2 RNA is a good predictor of inhibition of enterovirus RNA extracted from stool suspensions. EasyMag performed the best, however all four extraction methods were suitable provided that external controls identified problematic samples. Diagnosis of enteric viral infections by Real Time reverse transcription -polymerase chain reaction (rRT-PCR) of RNA extracted from stool suspensions is complementing and increasingly replacing diagnosis based on viral isolation and characterization in tissue culture [1, 2] . However, interpretation of results is not always straightforward. The sensitivity of the rRT-PCR is negatively impacted, by compounds present in the clinical sample that may partially or completely inhibit the RT and/or PCR chemistries [3, 4, 5, 6, 7] . Potential inhibitors that might be incompletely removed from stool suspensions during RNA extraction include hemoglobin, immunoglobulins, bilirubin, triglycerides, complex polysaccharides, organic and phenolic compounds, glycogen, fats, and metabolic products especially those from pathological conditions, bacteria, vegetables, medications, anticoagulants, and drugs or alcohol [4, 6, 8, 9, 10, 11] . Adding to the list of endogenous rRT-PCR inhibitors are exogenous inhibitors from extraction protocols such as detergents, chelating compounds and guanidinium HCl [9] .