Physiological indices of stress and ill-health (cortisol and salivary immunoglobulin A) were assessed to determine if they were predicted by Siegrist's effort-reward imbalance model (ERI) with an aim of identifying employees at risk of illness. Male Australian dairy farmers (N=66) completed the Perceived Stress Scale, Work related Questions II & III, Eysenck Personality Questionnaire Revised--Short and demographic questions and provided morning saliva samples (at awakening and 30 min post awakening) on a working day, which were subsequently analysed for cortisol and salivary immunoglobulin A (sIgA) concentration levels. A high percentage (45.5%) of the sample reported an imbalance between efforts and rewards in the workplace that may place them 'at risk' for ill-health. After controlling for disposition, sIgA scores were more successfully predicted by the ERI than the cortisol assessments. Although both efforts and rewards were significantly associated with sIgA, efforts were most strongly associated. The dispositional trait overcommitment, did not moderate the experience of stress on the physiologic indices. The current investigation supports the continued use of sIgA in studies that use biomarkers to assess occupational stress. ERI ratio scores >1 aligned with previous findings that suggest elevated risk of illness for these employees.