Purpose: To assess the effects of endometrial thickness and echogenicity on pregnancy and implantation rates in cases using assisted reproductive technology (ART). Methods: We retrospectively analyzed the data of 241 ART cycles performed at Istanbul Medical Faculty, Reproductive Endocrinology Unit. The cycles were classified into three groups according to ultrasonographic endometrial thickness measurements on the day of hCG application; 51 cases (group 1) <= 8 mm, 182 cases (group 2) between 8-14 mm, and eight cases (group 3) >= 14 mm. Also the cycles were grouped according to endometrial echogenicity as trilaminar, isoechogenic and hyperechogenic pattern. Results: There was no significant difference in pregnancy rates between the three endometrial thickness groups and echogenic patterns. When conception and non-conception cycles were compared, no significant difference in endometrial thickness was observed (9.88 +/- 1.83 mm vs 9.84 +/- 1.89 mm). Conclusion: Ultrasonographic evaluation of endometrial thickness and pattern is not useful in predicting implantation and conception rates in ART cycles.