Heat stroke (HS) remains a significant public health concern. Despite the substantial threat posed by HS, there is still no field or clinical test of HS severity. We suggested previously that circulating cardiac troponin (cTnI) could serve as a robust biomarker of HS severity after heating. In the current study, we hypothesized that cTnI band intensity on a portable point-of-care test (ctPOC) could be used to predict severity and organ damage at the onset of HS. Conscious male Fischer 344 rats (N=16) continuously monitored for HR, BP, and core temperature (T_c) (radiotelemetry) were heated to maximum T_c (T_c,Max) of 41.9 ± 0.1°C and recovered undisturbed for 24h at an ambient temperature of 20°C. Blood samples were taken at T_c,Max and 24hrs-post heat via submandibular bleed and analyzed on ctPOC test. POC cTnI band intensity was ranked using a simple 4 point scale via 2 blinded observers, and compared to cTnI levels measured by a clinical blood analyzer. Blood was also analyzed for biomarkers of systemic organ damage. HS severity, as previously defined using HR, BP, and recovery T_c profile during heat exposure, correlated strongly with cTnI (R² = 0.69) at T_c,Max. POC cTnI band intensity ranking accurately predicted cTnI levels (R² = 0.64) and HS severity (R² = 0.83). Five markers of systemic organ damage also correlated with ctPOC score (ALB, ALT, BUN, CHOL, TBIL; R² > 0.4). This suggests that cTnI POC tests can accurately determine HS severity and could serve as simple, portable, cost effective HS field tests.