This study was performed to identify the drug use and reuse relating characteristics and reuse relating factors in illegal drug users. Subjects consisted of 88 illegal drug users. Some of them were confined in a mental hospital or National Forensic Psychiatric Hospital located in Chung-nam province, others on attending a drug abuse prevention program in Seoul Probational Institute. Data were collected during the period from February 1, 2002 to February 25, 2002, and analyzed by SAS program. version 6.12. for Wilcoxon rank sum test, Pearson Correlation, Multiple regression. Results were as follows; 1. Drug use characteristics were as follows. $19.3\%$ was has drug family history and $20.7\%$ was has alcohol family history. Main drug was Phillopon$44.3\%$, inhalants $35.2\%$, LSD et al $22.7\%$. Drug use rate of months was everyday $31.2\%$, every other day $24.4\%$. 2. $100\%$ has experienced abstinence and reuse. Abstinence period was less than 12 months in $49.4\%$ and reuse period was less than 6 months in $58.6\%$. 3. Drug use and reuse characteristics related to general characteristics was identified as below. Abstinence period of male was longer than that of female. Person who have drug family history experienced more drugs and person who have family alcohol history started earlier. 4. Reuse periods was correlated with abstinence periods, age. And abstinence period was correlated with age and outcome that following reuse. 5. The multiple regression was used to identify the relating factors that influence reuse period and abstinence period. At the state of controlling abstinence period. inhalants users have 10.07 days shorter reuse period than others. And abstinence period had lengthened age, bad health status, early initiate age, and long reuse period.