Migration remains an important event in the urbanization process. However, research evidence indicates that
migration is associated with negative outcomes. For migrant youth, migration often coincides with leaving
home and divesting of parental authority and controls. This study investigates migration as a determinant of
risky sexual behaviours and the factors influencing the timing of first sex among migrant youth. We used data
collected between 2006 and 2008 from youth aged 12-22 years living in two slums in Nairobi. We use Cox
proportional hazards model for timing of first sex among migrants and logistic regression for determinants of
risky sexual behaviour. Migration is important for number of sexual partners but not for sexual debut. The
risk of initiating first sex soon after in-migration is higher for youth with problem behaviour. Among
adolescents in Nairobi’s slums, migration is not associated with a higher risk of engaging in risky sexual
behaviour. However, youth with problem behaviour face a higher risk of initiating sex soon after migration.