OBJECTIVES: Unintended pregnancies, a health problem with significant economic burden on US could be avoided by use of FDA approved oral emergency contraceptives (ECPs) namely Plan B one-step (one pill regimen) and Next choice (two pill regimen). The objective of this study was to conduct a head-to-head comparison of these oral ECPs.    METHODS: A cost effectiveness (CE) decision tree model was developed using data from published randomized controlled trails (effectiveness values) and primary data collection. Cost of each drug was obtained by taking an average of the price of drug from 5 large chain pharmacies. Outcomes considered were no pregnancy, birth, induced abortion, spontaneous abortion or ectopic pregnancy. Cost and probabilities of each outcome was derived from past literature and included only the direct costs. All adverse events with a probability of more than 5% and the direct cost associated with treating each of those adverse events were considered. These adverse events generally last for duration of one week, which was used to derive cost information for adverse events. The analysis involved only a onetime cost of taking an emergency contraceptive. Results were validated using one way and two way sensitivity analyses by varying the cost and effectiveness by a range of 25% each.  RESULTS: The brand name drug Plan B one-step as opposed to the generic counterpart available, Next Choice, emerged as the cost effective option to avoid unintended pregnancy. The cost of treatment with Plan B one-step was $859 as opposed to $1075 for Next Choice. Two-way sensitivity analyses were robust and indicated that treatment with Plan B one-step completely dominated Next Choice.CONCLUSIONS: Plan B one-step; a one pill emergency contraceptive drug, with a higher retail price was found to be more cost effective than Next Choice.