Leprosy is a chronic infectious disease caused by Mycobacterium leprae. Indonesia places the world's third major leprosy case contributor. Surabaya City is a leprosy-endemic area. This study aimed to early detect subclinical leprosy based on measurement of anti-PGL-1 antibody levels (IgM) and to determine factors related to subclinical leprosy among children in Surabaya City. This study was analitic using cross-sectional design. The study population was families having leprosy sufferers. Samples were selected by simple random sampling technique and 30 family heads were selected by rapid school and village survey on April – May 2015. Data was collected by interview using questionnaire. Specimen was taken from peripheral blood of fingertip using capillary tube and filter paper method. Serological test was conducted in Airlangga University Leprosy Laboratory of Institute of Tropical Diseases to determine leprosy-specific antibody levels using ELISA method. Seropositive result as cut off point determined ≥ 245 u/ml showed subclinical leprosy. Results of serological test showed eight respondents (26.7%) were positive suffering subclinical leprosy. Results of analysis using chi-square test showed contact record (p value = 0.034; RP = 4.500) and duration of contact (p value = 0.028; RP = 5.182) were factors related to subclinical leprosy infection among children. Serological test of anti-PGL-1 antibody levels (IgM) was used in subclinical leprosy-screening activity.