<b><i>Purpose:</i></b> This study aimed to investigate the clinical features and treatment outcomes of idiopathic full-thickness macular hole (FTMH) without vitreomacular separation (VMS). <b><i>Methods:</i></b> Consecutive cases of idiopathic FTMH at one tertiary center from January 2013 to April 2020 were retrospectively recruited. They were separated into two groups according to the findings in optical coherence tomography (OCT): FTMH with VMS and FTMH without VMS. Ophthalmic examinations and OCT were performed pre- and postoperatively. The clinical findings were compared between the two groups. <b><i>Results:</i></b> Of the total 124 cases, 15 (12.1%) were noted as FTMH without VMS with the presence of an attached posterior hyaloid (PH) at macula. The macular hole (MH) size was smaller (276.06 ± 170.10 μm) compared to those with VMS (492.83 ± 209.31 μm) (<i>p</i> &#x3c; 0.001). The incidence of lamellar hole-associated epiretinal proliferation (LHEP) was much higher in this group (13/15, 86.7%) compared to FTMH with VMS (11/109, 10.1%) (<i>p</i> &#x3c; 0.001). A higher rate of spontaneous closure of MH (13.3%) was also noted in FMTH without VMS (13.3% vs. 0.9% in FTMH with VMS, <i>p</i> = 0.040). After operation, the MH closure rate was 93.3%. The postoperative best-corrected visual acuity was not significantly different between the two groups (<i>p</i> = 0.098). <b><i>Conclusions:</i></b> A small percentage (12.1% in this series) of idiopathic FTMH had no VMS. The completely attached PH along with the high incidence of LHEP implied a tangential traction in FTMH without VMS. The MH size was usually small, and the postoperative outcomes were similar to those of conventional FTMH with VMS.