Technical Abstract: Tibial dyschondroplasia (TD) is a major poultry leg problem the natural etiology of which is unknown. Certain dithiocarbamate pesticides such as tetramethyl thiuram disulfide (thiram) have been shown to induce the disease in chickens. Since many different carbamate and thiocarbamate chemicals are used in a number of agricultural, industrial, and house hold applications, the objective of this study was to determine whether all chemicals of these categories induce TD and whether there is a concentration dependent relationship between the ingestion of these chemicals and the incidences and the severity of the disease. Week-old broiler chicks were fed diets containing thiram or other assorted carbamate and thiocarbamate pesticides mixed in feed for 24-48 hr between ages 8 and 10 days. The birds were killed on day 15 and the proximal tibial and tarsometatarsal growth plates were evaluated for the presence and severity of TD lesion. TD was distinguished by broadening of growth plates with histological features of chondrocytes that were shrunken and dead. When compared by including equimolar concentrations of these chemicals in the feed, the dithiocarbamates with more than two sulfide groups such as disulfiram, ferbam, thiram, and ziram were potent inducers of TD, whereas those with two sulfides to no sulfide group appeared ineffective. Both thiram and ferbam also reduced the bird’s body weights. Thiram increased the incidence and the severity of the disease denoted by TD index in a dose dependent manner. These results suggest that inadvertent contamination of feed or litter with some of these or similar chemicals may cause leg problems in poultry.