Young women may present with decreased ovarian reserve (DOR) and/or poor oocyte quality. These may lead to poor reproductive outcomes. Our retrospective study evaluated the association between oocyte quality and ovarian reserve in women aged between 18 and 35 years and undergoing controlled ovarian stimulation (COS) for in vitro fertilization. We defined DOR when anti-Müllerian hormone (AMH) levels were <1.2 ng/mL, basal follicle stimulating hormone (FSH) levels were ≥10 mIU/mL, or the antral follicle count (AFC) was <10 and analyzed the association between the number of mature or immature oocytes and the presence of alterations in oocyte morphology. We also evaluated the association between gonadotropin dose used in COS and oocyte quality. The study included 49 patients with a mean age of 31.0 ± 3.3 years; 348 oocyte images were evaluated. Patients with basal FSH levels of <10 mIU/mL had more mature oocytes than the group of patients with elevated FSH levels (6 vs. 2; p < 0.001). Patients with AMH<1.2 ng/mL had fewer mature oocytes and increased basal FSH levels (p < 0.001). Each unit increase in serum basal FSH levels represented a 42% increase in the likelihood of having an oocyte with cytoplasm abnormality (p = 0.006), while patients with AMH levels of <1.2 ng/mL had 5.3 times the risk of having an oocyte with cytoplasm abnormality [p = 0.004] and were 3 times more likely to have an abnormality in the perivitelline space (p = 0.018). When the AFC was <10, an increased risk of abnormally shaped oocytes was observed (p = 0.035). In summary, DOR was associated with poorer quality oocytes in women up to 35 years of age who underwent COS.