Illegal immigrants are people who enter and reside in the country without proper visa or permit. Threat is warning that a person is going to be hurt or be punished. It is sometimes a sign of possible danger. This book finds out threats caused by illegal immigrants to recipient country; it looked what impacts illegal immigrants brought to the security of people especially to those living in areas bordering with Rwanda and Burundi. The author found that threats were the results of political instability and civil wars in the neighboring countries of Rwanda and Burundi which caused weapons to penetrate and spread to Tanzania easily. Demobilization of extra soldiers after the wars in Rwanda and Burundi resulted to those soldiers to look for whatever to survive with. Hence entered to Tanzania and made raids for economic gain. Moreover corruption on the part of local leaders spearheaded the problem. The long term solutions to such problem are seminars to immigration officers, police officers and local leaders. Education to the masses, increase of manpower (employees), more motivations and rewards to workers can also solve the problem.