▪Erectile dysfunction (ED) is a multidimensional disturbance of the erectile response involving organic, relational and psychological components, which has been reported to affect a significant proportion of patients after allogeneic hematopoietic stem cell transplant (HSCT). Although predictors for ED have been established in the general population, few studies have addressed which variables are associated with ED in HSCT patients.Aims of the study were to establish prevalence and extent of ED in 55 consecutive patients transplanted in our Institution between 2003 and 2015, and to identify within socio-demographic, medical and psychological domains eventual ED predictors.Patients were enrolled in the study upon informed consent. Inclusion criteria were age ≥ 18 years, continuous disease remission, and ≥ 6 months from HSCT. Exclusion criteria were concurrent malignancy, major psychiatric disorder or mental retardation, and hormonal replacement.ED was assessed and measured by the International Index of Erectile Dysfunction (IIEF15).Patient socio-demographics were collected by an ad hoc schedule.Medical data were obtained from hospital records. The andrological visit included testicular measure, penis and genital skin inspection, and penile ultrasound and elastosonography. Free testosterone (FT), inhibin B, follicle stimulating hormone (FSH), luteinizing hormone (LH), prolactin, thyroid stimulating hormone (TSH), free triiodothyronine 3 (FT3), FT4, cortisol, and adrenocorticotropic hormone (ACTH) levels were measured.Anxiety was quantified by the State-Trait Anxiety Inventory (STAI), depression by the Zung Self-rating Depression Scale (SDS).Differences between groups were analyzed by the non-parametric Mann-Whitney test and the Fisher's exact test when testing quantitative and categorical variables, respectively. Logistic regression analysis was used to estimate the association of the variables predictive for ED, when including into the association model the relevant covariates. Chronic graft versus host disease (cGVHD) was diagnosed according to NIH criteria.Fifty-two (94.5%) of the 55 patients eligible for the study returned the self-administered questionnaires and underwent the andrological visit: 32 had acute leukemia, 7 non-Hodgkin lymphoma, 4 myelodysplastic syndrome, 4 chronic myeloproliferative disease, 3 multiple myeloma, 2 B cell chronic lymphocytic leukemia.Median time from HSCT to study assessment was 19 (6-108) months. Thirty-nine patients (75%) had hypogonadism, while 10 (19.2%) presented genital cGVHD, with post-HSCT phimosis in 7 cases, meatal scarring in 2, lichen sclerosis-like lesions in 1. At penile ultrasound and elastosonography, 12 (23%) and 7 (13.5%) patients had a medium-hard and hard penile elasticity.FT and inhibin B were below the range limit in 34 (65.4%) and 33 (63.5%) patients, while FSH was above in 47 (90.4%), thus indicating a large prevalence of gonadal failure. Three patients (5.7%) had a mild hypotyrodism. No prolactin, cortisol or ACTH alterations were observed.Forty-seven (90.4%) of the 52 participants declared a stable sexual partner: the 5 patients [median age 42 (19-50) years, 1 with cGVHD] who reported not having any sexual activity due to partner absence were excluded from the analysis of ED predictors according to IIEF15 requirements.ED was reported by 31/47 (66%) patients: it was severe in 42% cases, moderate in 22.6%, moderate to mild in 6.4% and mild in 29%. There was no difference between patients with and without ED in terms of time from HSCT [25 (6-108) vs 15 (6-79) months, p=0.32].In univariate analysis higher age, low education level, and cGVHD (excluding the isolated genital one) were significantly associated to ED, while the same variables in addition to hypertension maintained their significance in the subgroup of patients with moderate-severe ED only (Table 1). In a logistic regression model, age and cGVHD were the only variables independently associated with ED (any grade, p=0.02 and moderate-severe, p=0.0001, respectively).Our study confirms that ED is a frequent long-term complication of HSCT, with cGVHD being a major predictor. We suggest that an early screening of sexual dysfunction and a close partnership between HSCT clinicians and andrologists could help to implement reliable prevention strategies and/or prompt interventions for patients suffering from ED. [Display omitted] DisclosuresNo relevant conflicts of interest to declare.