Median nerve abnormalities are common but not well studied on a population basis. Baseline data from an ongoing cohort (n = 683) in 12 diverse plants in Wisconsin and Utah are reported. The workers are 66.1% female, 27.7% current and 23.9% former smokers, with a mean age of 40.7+/-11.3 years and mean Body Mass Index (BMI) of 28.5+/-6.4 kg/m2. All workers underwent a questionnaire, structured interview, physical examinations and a nerve conduction study (NCS) of both extremities. The one month period prevalence of tingling/numbness in the right and left hand was 38.9% and 32.8% respectively. Results from the NCS on the right /left hands were 18.3%/3.5% mildly and 6.1 %/1.2% moderately/severely abnormal. Multiple logistic regression (SAS) was performed. Stratified analyses for both the right and left hands showed increasing age [Odds Ratio (OR) = 1.03 95% [Confidence Interval (CI) 1.01,1.05], 1.04 (95% CI 1.02, 1.07) respectively], BMI [OR = 1.09 (95% CI 1.06, 1.12)1,.10 (95% CI 1.06, 1.15)], and exacerbation of numbness/tingling at night [OR = 2.96 (95% CI 1.89, 4.71), 2.79 (95% CI 1.50,5.19)] to be statistically significantly associated with an abnormal NCS. Diabetes [OR = 2.70 (95% CI 1.20, 6.10], and exacerbation of numbness and/or tingling when holding an object [OR= 2.72 (95% CI 1.42, 5.46) were statistically significantly associated with abnormal left hand NCS. Diabetes and exacerbation of numbness and/or tingling when holding an object trended towards statistically significance in the right hand. These results show a relatively high prevalence of paraesthesias in a large population.