Prisoners are at risk for both physical and psychological diseases. Here, we report an outbreak of peripheral neuropathy in a prison in northeast Thailand. Between July and December 2014, there were 88 male prisoners at Bueng Kan Provincial Prison in Bueng Kan, Thailand suffering from peripheral neuropathy out of a total of 1,464 prisoners (6.01%). The common age range was 20-39 years (58 patients; 65.91%). The three most common features were hyporeflexia/areflexia of the lower extremities (36 patients; 83.72%). On laboratory vitamin B1 deficiency was detected in 4/5 patients, positive rhinovirus polymerase chain reaction in 3/4 patients, positive Mycoplasma pneumoniae IgM in 1/12 patients, and positive urinary arsenic in 4/7 patients. A dT vaccination was given on October 14 during the outbreak. This was a large outbreak of peripheral neuropathy in male prisoners. There are several possible causes of this outbreak including vitamin B1 deficiency, dT vaccination, arsenic toxicity, rhinovirus, and Mycoplasma infection.