We　present　the　top-bottom　effect　(TBE)　of　a　5　mu　m　thick　amorphous　specimen　in　a　3　MV　ultrahigh　voltage　electron　microscope　(ultra-HVEM)　and　its　influence　on　the　quality　of　electron　tomography　(ET).　The　40-nm　gold　particles　on　the　top　surface　of　the　specimen　tilted　at　different　angles　have　been　observed　to　be　of　poorer　image　quality　than　those　on　the　symmetrical　bottom　surface　obtained　by　tilting　and　turning　over　the　specimen.　The　point　spread　function　of　the　gold-particle　images　was　calculated　using　the　increment　Wiener　filter　and　the　image-quality　variation　was　then　evaluated.　The　TBE　is　shown　to　become　more　remarkable　with　the　increase　of　the　effective　thickness　of　the　tilted　specimen　or　the　decrease　of　the　magnification　of　the　ultra-HVEM.　The　ET　simulation　indicates　that　the　TBE　may　generate　similar　to　4%　distortion　in　the　radial　direction　of　a　reconstructed　sphere　model.