Background: Onychomycosis is a commonly encountered superficial fungal infection. Beside causative dermatophytes and yeasts, present data shows that non-dermatophytic filamentous fungi can also be the potential cause of this ungual disease. The aim of this study was to analyse the causative agents of onychomycosis in patients attending dermatology OPD of a tertiary care hospital. Methods: A mycological study of onychomycosis was undertaken in 881 patients suspected to have fungal nail infection by their clinical appearance referred from the Dermatology OPD, January 2016 to July 2018 and processed in the Department of Microbiology RIMS. Direct microscopy of the nail clippings in 10% KOH followed by culture in SDA and DTM was performed to identify the causative agent. Results: Direct microscopy of the nail clippings in 10% KOH was positive in 318 (35%) and culture was positive in 592 (67.1%) cases. Out of the samples cultured, dermatophytes were grown in 166 (28.04%), non – dermatophytes moulds grown in 331 (55.9%), yeast and yeast like grown in 73 (10.8%) and mixed isolates grown in 22 (3.7%) Among the dermatophytes Trichophyton spp. was found to be commonest etiological agent followed by Microsporum spp. Among the non – dermatophyte moulds Aspergillus spp. was the most prevalent species followed by Penicillium spp. Conclusions: In the previous study done during the period from January 2013 to December 2015 in RIMS Imphal, among the dermatophytes Trichophyton spp. was the commonest followed by Epidermophyton species. Among non-dermatophytes Aspergillus species was the commonest followed by Fusarium species that caused onychomycosis. The prevalence of non-dermatophytic onychomycosis was more than the dermatophytic onychomycosis. Here in this comparative study the change in the trend of onychomycosis is not very significant. Hence the trend of onychomycosis by dermatophytes and Non-dermatophytes remains the same in RIMS Hospital.