Background Characterization of drug resistance mutations and signature pattern in the archived DNA of HIV-1 infected North Indian patients.Methods Blood samples were collected from 9 patients enrolled in ART Centre, S.N. Medical College, Agra, North India from 1 year to = < 7 years. DNA was isolated and amplified for protease and reverse transcriptase genes using nested primers from WHO dried blood spot protocol 2010. The polymerase chain reaction products were sequenced and drug resistance mutation patterns were analysed using the HIV drug resistance database, Stanford University, USA. Various computational tools and websites like Stanford HIV drug resistance database, Viral epidemiological signature pattern analysis (VESPA), Hypermutation, SNAP version 2.1.1, Entropy were utilized for analysis of the sequence data.Results This study enables an analysis of archived DNA samples in patients having lower viral load and where the situation of HIV RNA isolation was negligible. Lamivudine associated drug-resistant mutations such as M184V/M184I, nevirapine associated mutations Y181C and H221Y and efavirenz associated mutations M230I were observed in two patients. No mutations were observed in the remaining seven patients. The signature pattern analysis of 9 protease and reverse transcriptase genes identified the conservation of amino acid sequences as compared to the reference sequence. The signature pattern of nucleotide substitution (synonymous to non-synonymous ratio) of the protease gene was 5.02 and the reverse transcriptase gene was 7.01. No hyper mutation was observed in the protease and reverse transcriptase gene of the archived DNA.Conclusions The analysis of the drug resistance mutation in the protease and reverse transcriptase gene of the archived DNA of HIV-1 subtype C infected patients over 1 to = < 7 years of first-line ART may be helpful in the treatment guideline in North Indian patients. A few signature amino acids were persisted in the reverse transcriptase and protease gene of similar HIV-1 subtype C infected patients over 1 to = < 7 years of first line ART in comparison to the reference sequence. This archived DNA drug resistance mutation testing could be an important tool when RNA testing becomes unsuccessful.