Objective Adult granulosa cell tumors (AGCTs) represent 2%–5% of all ovarian malignancies. The aim of this study was to analyze clinical and pathohistological parameters and their impact on recurrence, overall, and disease-free survival in FIGO stage I AGCT patients. Methods The tumor specimens analyzed in this retrospective study were obtained from a total of 36 patients with diagnosis of ovarian AGCT surgically treated at the Department of Gynecology, Rijeka University Hospital Centre, between 1994 and 2012. Clinical, pathological, and follow-up data were collected. Results The mean age at diagnosis was 54.5 years with a range of 24–84. The majority of the patients, 30 (83%), were in FIGO stage IA, 3 (8%) in stage IC1, 1 (3%) in stage IC2, and 2 (6%) in stage IC3. During follow-up period (median 117.5 months, range 26–276), recurrence occurred in 4 patients (12%) with 2 deaths of the disease recorded. In univariate analysis, the 5-year survival rates were significantly shorter in patients with FIGO substage IC (p = 0.019), with positive LVSI (p = 0.022), with presence of necrosis (p = 0.040), and with hemorrhage (p = 0.017). In univariate analysis, the 5-year disease-free survival rates were significantly shorter in patients treated with fertility surgery (p = 0.004), with diffuse growth pattern (p = 0.012), with moderate and severe nuclear atypia (p = 0.032), and with presence of hemorrhage (p = 0.022). FIGO substage IC proved to be independent predictor for recurrence (OR = 16.87, p = 0.015, and OR = 23.49, p = 0.023, resp.) and disease-free survival (p = 0.0002; HR 20.84, p = 0.02) at the uni- and multivariate analyses. Conclusions FIGO substage IC is predictive of recurrence and disease-free survival in patients with early-stage AGCTs. LVSI, presence of necrosis and hemorrhage, diffuse growth pattern, and nuclear atypia in AGCTs seem to be associated with overall and disease-free survival, so these pathological features should be taken into consideration when managing patients with AGCT.