Perlutal (other names: Topasel, Perlutan) is a once-a-month injectable contraceptive that contains 10 mg estradiol enanthate and 150 mg dihydroxyprogesterone acetophenide. A prospective trial was conducted in 216 women in Medellín, Colombia, over five years (5,462 woman-months) to establish the rates of the different vaginal bleeding patterns during the use of Perlutal, and to assess their relation with discontinuation of the Perlutal regimen. It was found that with the use of Perlutal, the duration of menstrual bleeding decreased from 3.9 to 2.7 days (p < 0.01), and that the incidence of dysmenorrhea decreased from 31% to 1.6% (p < 0.01). At one year of follow-up, the incidence of altered bleeding patterns was 5.1%. The discontinuation rate due to an altered bleeding pattern was 3.9%. It is concluded that the low incidence of altered bleeding patterns observed with the use of Perlutal leads to a low discontinuation rate among users.