The aim of this multi-centre case-control study, whose main research objective is to investigate the relationship between occupational exposure to manual materials handling and/or working postures with trunk inclination and disc-related diseases of the lumbar spine, is to investigate the dose-response relationship between psychosocial job strain and lumbar disc herniation as well as lumbar disc chondrosis. 286 male (case group 1) and 278 female subjects (case group 2) with lumbar disc herniation and 145 male (case group 3) and 206 female subjects (case group 4) with lumbar chondrosis and 901 population control subjects (453 men, 448 women) between 25 and 70 years of age were recruited in four study regions in Germany (Frankfurt am Main, Freiburg, Halle, Regensburg). The control subjects were drawn from the regional population registers. The data on psychosocial job strain was collected using the screening method "FIT" (Questionnaire on perceived work intensity and activity latitude) with the two strain factors "work intensity" and "activity/decision latitude " in the course of a structured personal interview. The "situational spinal load" (compressiveforce on the lumbosacral disc) was determined by means of biomechanical simulation calculations ("The Dortmunder") on the basis of the data of an expert interview ("TAD-Interview "). Using this data the "cumulative lumbar load" was estimated using 10 alternative dose models. TheAkaike information criterion (AIC) was used to measure the goodness of fit of the single dose model for the four case groups to illustrate the relationship between cumulative spinal load and lumbar chondrosis or lumbar disc herniation, respectively. Confounder selection was based on biological plausibility and the "change-in-estimate criterion ". In the epidemiological analysis Odds ratios (OR) and the 95% confidence intervals (CI) were calculated using unconditional logistical regression analysis, adjusted for age and study centre as well as the most appropriate dose model. The case-control study reveals a statistically significant positive relationship between psychosocial job strain and the development of a lumbar chondrosis among women. We find a monotonous dose-response relationship (OR for the highest exposure category =4.0; CI=2.0-8.1). The statistical relationship between occupational psychosocial strain and the development of a lumbar chondrosis in men (OR for the highest exposure = 2.3; CI=1.0- 5.3) as well as the development of a lumbar disc herniation among men and among women is mar-German Spine Study EPILlFT - psychosocial strain - lumbar disc herniation - lumbar chondrosis - doseresponse relationship ginally significantly positive. We find a monotonous dose-response relationship (OR in the second-highest exposure category for men=1.4; CI=0.9- 2.2; for women=1.5; Cl = 1.0-2.2) in subjects with lumbar disc herniation. The results could be explained by selection bias or inadequate operationalization of psychosocial strain by only two strain factors. This case-control study reveals a relationship between occupational psychosocial strain and the development of lumbar disc herniation as well as lumbar chondrosis among men and women. The relationship with lumbar chondrosis among women is statistically significant positive.