The main mission of Kamiti Maximum prison is to rehabilitate its inmates in order to make good citizens once they are out of the facility. Contraband on the other hand finds their way into the prison via different means hence posing a great challenge to the process of rehabilitation. The aim of this study therefore was to find out how the contraband are smuggled into prison, why inmates use contraband and to examine the effect of contraband on inmates‟ rehabilitation. This qualitative research among 36 Prison Officers and 70 inmates examined the effect and use of contraband. It is clear that there are several routes of entry and reasons why inmates use contraband. This study has shown that the most popular routes of entry is through members of staff, during social visits and contraband thrown over perimeter walls of the prison at 25%, 19% and 17% respectively. Majority of inmates (63%) use contraband as a form of currency to make prison life more comfortable and maintain own contraband use. This study also reveals the negative effect associated with contraband use including an increase in insecurity, namely bullying, violence and withdrawal. It is essential that prisons provide adequate detoxification to reduce withdrawal symptoms and alleviate their need to import or purchase illegal drugs. Prisons must increase their efforts to reduce supply. This will reduce opportunistic use, and with it the risk of prisoners developing „jail habits‟ in custody. Devising a policy for tackling contraband in prison is prudent for major contribution in reducing criminal behaviour in prison as well as offences outside prisons. Finally it is essential to recognise that increased security has significant effects; it can disorganise and eliminate contraband supply routes.