Tujuan penelitian untuk mengkaji keabsahan dan akibat hukum pelaksanaan lelang barang jaminan Hak Tanggungan yang dilakukan tanpa pemberitahuan kepada Debitur dan tanpa pengumuman lelang. Penelitian dilaksanakan dengan yuridis normatif memakai pendekatan kasus dan pendekatan perunndang-unndangan. Hasil penelitian yaitu pelaksanaan lelang barang jaminan dengan tanpa pemberitahuan kepada Debitur dan tanpa pengumuman lelang adalah tidak sah, karena tidak sesuai pada prosedurnya lelang sesuai Permenkeu RI juga tidak memenuhi asas publisitas, keterbukaan dan dapat dipertanggungjawabkan. Sedangkan, akibat hukum pelaksanaan lelang yang dilakukan tanpa pemberitahuan kepada Debitur dan tanpa pengumuman lelang adalah dapat dibatalkan. Kata Kunci: Lelang, Hak Tanggungan, Debitur. This research has as purpose to examine the validity and legal consequences if the auction of mortgage collateral is carried out without notification to the debtor and without an announcement of the auction. The research was conducted by normtive juridical using a case approach and statute approach. The research results showed that auction execution guarantee which is conducted without notification to the debtor and without auction announcement is invalid, because it is not in accordance with the auction procedure as regulated in the regulation of the minister of finance of the Republic of Indonesian and does not meet the principle of publicity, principle of transparency and principle of accountibility. While, legal consequences of the auction is without notification to the debtor and without an announcement of the auction voidable. Keywords: Auction, Mortgage, Debtor.