Abstract The purposes of this study were to evaluate and compare the technical feasibility and the patients’pain during hysterosalpingo-foamsonography (HyFoSy) using two differ-ent 2-mm balloon catheters. Randomized trial in 46 consecu-tive women referred for tubal patency testing by HyFoSy at the Leuven University Hospital. Six women refused to partic-ipate. Forty women were randomized and blinded as to the catheter used. The patients underwent first a transvaginal ultrasound examination to assess the uterus and the ovaries and to exclude the hydrosalpinx, and subsequently, a HyFoSy was performed using an uVue catheter (Cook Medical, Bloomington, IN, USA) or a pediatric Foley’scatheterwith stylet (Pediatric Folysil, Coloplast A/S; Humlebaek, Den-mark) according to randomization. If the catheter could not be inserted smoothly into the uterine cavity at first attempt, transabdominal ultrasound guidance was performed. After the procedure, the patients were asked to fill in a questionnaire including a visual analog scale (VAS) score for the pain at initial ultrasound examination (VASUS), used as baseline score, and at HyFoSy (VASHyFoSy). The pain related to the HyFoSy procedure was reported as (VASHyFoSy−VASUS)/ VASUS. Catheter insertion failed in one patient of the uVue group (5 % failure rate) and in none of the Foley group. Ultrasound guidance during catheter insertion was performed in 68 % of the uVue group and 20 % of the Foley group. The median ratio (VASHyFoSy−VASUS)/VASUSfor the uVue and the Foley group was 1.82 and 0.54, respectively (p=0.005). A pediatric Foley catheter was easier to insert as compared to an uVue catheter, and HyFoSy using a pediatric Foley catheter was reported by the women to be the least painful