The work explores the effects of halloysite nanotubes (HNT) on the structure and properties of epsilon-polycaprolactone/gelatin (PCL/Gel) nanofibers. Electrospun nanofibers containing 8 wt% Gel and 8 wt% PCL have been prepared by using tissue-friendly solventacetic acid. The HNT content in nanofibers has been varied from 0.5 up to 6.0 wt%. The results revealed significant effect of HNT on the obtained nanofiber structure and fiber diameter. Nanofibers with lower HNT concentration provided fibrous structure with HNT particles located predominantly inside the individual fibers. In the case of nanofibers with 6 wt% HNT, the individual particles as well as the agglomerates of HNT have been detected. The highest improvement of mechanical properties (strengthfrom 1.3 +/- 0.1 MPa to 2.2 +/- 0.2 MPa and elongationfrom 17.5 +/- 5.0% to 61.1 +/- 7.7%) has been achieved when the content of HNT in nanofibers was equal to 0.5 wt%. The addition of HNT also improved the thermal stability and reduced the crystallinity of PCL/Gel nanofibers. The proliferation of NIH-3T3 fibroblasts on PCL/Gel nanofibers was qualitatively observed using fluorescence microscopy. The cells appeared well adhered and characterized by normal fibroblastic behavior on all examined nanofibers. POLYM. ENG. SCI., 57:506-512, 2017. (c) 2017 Society of Plastics Engineers