Background: Of an estimated 210 million pregnancies that occur in the world each year, 38% are unplanned, out of which 22% end in abortion. In Ethiopia, the estimates of unintended pregnancy indicate that it is one of the major reproductive health problems with all its adverse outcomes. Objective: The objective of this study was to assess the prevalence of unintended pregnancy and its associated factors among pregnant women in Welkaite district, Tigray region, northwest Ethiopia. Methods: Acommunity based cross sectional study was conducted from 24/09/2012 to 18/10/2012 among pregnant women. The study includes 626 pregnant women found in Welkaite district selected from the study population using cluster sampling technique. A structured questionnaire was used for data collection. Data were analyzed using SPSS. Adjusted Odds Ratio was used to assess the strength of association and declare significance of the associations. Results: Unintended pregnancy was reported by 26% (166/626) of the study subjects. Out of which, 75.9% were mistimed and 24.1% were unwanted pregnancy. Unintended pregnancy was associated with ante natal visit (AOR=3.434;95%CI:2.136,5.520), awareness of contraceptive (AOR=2.830;95% CI: 1.527,5.244)., husband communication about pregnancy (AOR=2. 245; 95% CI: 1.430,3.524) , awareness of the concept of unintended pregnancy is preventable (AOR=2. 563 ; 95% CI: 1.580,4.158). Conclusions: In this study prevalence was high, and,women’s decision to follow antenatal care, and antenatal care visit, ever heard contraceptive communication with husband were strong predictors of unintended pregnancy. Recommendation: Women’s need to be, strength, communication with husband about pregnancy, antenatal care follow up, and women’s information, education; communication programs and improvements in counseling about contraceptive is recommended to decrease unintended pregnancy