The aim of this study was to evaluate the correlations of stress hormone responses, rating of perceived exertion (RPE) and training intensity of duet synchronised swimmers during pool training sessions over a 1-week training cycle. Five synchronised swimmers (21±3 years, body mass 52±4 kg, height 163±3 cm) undertook their weekly pool training session. A 2-min saliva sample was collected before and after training for the analysis of salivary cortisol. Total training time, heart rate and rating of RPE were recorded at the end of the session. Exercise intensity was defined as “light” (≤54%), “moderate” (55%-69%), “high” (70%-89%) and “very high” (≥90%) in relation to maximum heart rate. Swimmers spent 39%, 34%, 25% and 2% of their total training time for light, moderate, high and very high intensity, respectively. Post-training salivary cortisol was correlated with RPE (r=0.64, p<0.005). Post-training salivary cortisol and RPE was correlated with all four intensities, (p<0.000; p<0.001; p<0.000; p<0.005); the increase in post-training cortisol and RPE was highly correlated with high intensity training (r=0.68, p<0.000). The results show that post-training salivary cortisol and RPE are closely correlated and are highly correlated to high intensity in synchronised swimmers' pool training. Both salivary cortisol and RPE can be used to indicate the pool session training intensity accurately.