Background & Objectives: Unintended pregnancy is a worldwide problem. Despite abundant efforts by lranian family planning authorities during the last decade, unintended pregnancy and its consequences such as infected abortions is still a common problem. The aim of this descriptive study was to examine the causes of unintended pregnancy in Kosar Hospital, Urmia.

  M e thods : In this descriptive-analytical study the data were collected from 330 unintendedly pregnant women (out of 1830 pegnant women) visiting gynecology unit at Koshar Hospital in Urmia in 1999. These subjects were interviewed to fill out a questionnaire. Statistical analyses were performed with SPSS using t-test and Chi-square.

 Results: 83.6% of the cases were illiterate and 96.36% were housewives. 59.69% of the cases were above 30 79.09% had 3 or more children. The subjects used the following prophylaxy.

 Methods: thads. Pills (40%), withdrawal (25.5%), IUD (10%), injection (6.4%), minipills (4.5%), condom (3.6%) breast feeding (2.7%), rhythmic (0.9%) and tubectomy (0.6%). The remaining 5.8% had not used any prevention methods. We found a significant correlation between aging and number of unwanted pregnancies (P<0.0001 r = 0.44) and a negative meaningful correlation between literacy and rate of pregnancy (P<0.0001 r = 0.39). Reasons for failure were irregular use of pills, minipills or condom (90% each), unfamiliarity with prevention affter forgetting to take the pill (0.77%), IUD extraction, interrupted use of DMPA method and incorrect use of breast feeding method.

 Conclusion: This study reveals that desptie available prevention methods, due to lack of knowledge irregular use and misconceptions about complications of prevention methods, the subjects used unreliable methods which are more likely to lead to failure. Therefore, new measures should be taken in family planning centers to increase awareness among women concerning risk of unitended pregnancy.