This study was conducted to examine the excretion rate of dimethylformamide (DMF) from the workers exposed to DMF. The study was done at two synthetic leather factories located in Kyeonggi-do from the period of May 2 to 30, 1996. N-methyl- formamide (NMF) concentrations in urine were measured and compared by the three exposure level of DMF in air. The mean concentration of the Low (dry and winder part). Moderate (rinsing part) and High (mixing and coating part) exposure group were 3.99+/-3.54. 10.19 +/-5.69 and 32.10+/-7.87 mg/m3 during workshift of 8 hours, respectively. The mean concentration of urinary N-methylforinamide (NMF) were 2.13+/-2.58, 11.16+/-4.98 and 26.24 +/-7.35 mg/g creatinine, respectively. The concentration of NMIF in urine could reach to maximum in 3 hours and was reduced nearly to zero in about 18 hours after exposure to DMF.