Insemination refers to the placement of washed and prepared sperm into the uterus in an attempt to achieve pregnancy, using semen from the male partner or from a donor. 
For men :

•  Ejaculation failure [ because of diabetes, multiple sclerosis, spinal cord injury and  retrograde ejaculation,    psychological]
•  Low sperm count
•  Poor sperm quality
•  Anti Sperm Anti bodies
•  Freezing of semen for future IUI use [for the men who is undergoing vasectomy,  chemotherapy or            radiotherapy] when husband is away.

For Women :

•  Mild endometriosis
•  Cervical mucus hostility

Combined factor :

•  Unexplained infertility

Indication for Donor Insemination [DI] :

•  For single women

•  When other treatments for male factor infertility are not possible or were unsuccessful  [ICSI,Varicocele     repair etc]
•  When the male partner is a carrier of undesirable hereditary disease
    When couple cannot afford IVF - ICSI