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| Nydal Fysioterapi Og Helse AS | Furnes | 2013 |
| Nydalen Barnelegesenter AS | Oslo | 2011 |
| Nydalen Kiropraktorklinikk AS | Oslo | 2016 |
| Nydalen Legesenter Da | Oslo | 2015 |
| Nydalen Medisinske Senter AS | Oslo | 2017 |
| Nydalen Tannlegesenter AS | Oslo | 2016 |
| Nye Anita Midtun Legetjenester AS | Fana | 2026 |
| Nye B&B Drift AS | Oslo | 2023 |
| Nye Eirik Aukland Legetjenester AS | Bergen | 2026 |
| Nye Flattum Tannlegesenter AS | Hønefoss | 2026 |
| Nye Gitte & Thomas AS | Trondheim | 2026 |
| Nye Ha Tannlege AS | Hamar | 2026 |
| Nye Hudlegeklinikken Innlandet AS | Lillehammer | 2024 |
| Nye Hudlegekontoret Lillehammer AS | Oslo | 2024 |
| Nye JR Hellevik Holding AS | Arendal | 2017 |
| Nye Kjeveortoped Rao AS | Fannrem | 2026 |
| Nye Laser Holding AS | Lierstranda | 2023 |
| Nye Lillestrøm Øre Nese Hals AS | Lillestrøm | 2021 |
| Nye Sandviksboder Legepraksis Da | Bergen | 2012 |
| Nye Schneider AS | Tønsberg | 2016 |
| Nye Sentrumklinikken AS | Kristiansand S | 2026 |
| Nye Spire Psykologtjeneste AS | Kristiansand S | 2018 |
| Nye Sætre Tannlegesenter AS | Sætre | 2023 |
| Nygaard Dental AS | Asker | 2019 |
| Nygård & Nygård Consulting AS | Haugesund | 2013 |
| Nygårdsgaten Legesenter Da | Bergen | 2013 |
| Nymo Health AS | Hagan | 2019 |
| Nymoen Legekontor AS | Kongsberg | 1990 |
| Nymosvingen Legesenter AS | Lillehammer | 2024 |
| Nystedt Holding AS | Høvik | 2005 |
| Nytorget Legesenter AS | Stavanger | 2012 |
| Nytt Selskap AS | Kleppestø | 2025 |
| Nytt Smil AS | Oslo | 2021 |
| Nyttsyn AS | Stavanger | 2025 |
| Nedre Eiker Legesenter A/S | Mjøndalen | 1987 |
| Nåløye AS | Oslo | 2015 |
| Næring Og Nærhet AS | Fagerstrand | 2024 |
| Næringstjenester AS | Vestby | 1995 |
| Nærlege AS | Skogsvåg | 2026 |
| Nærmestring AS | Rørvik | 2023 |
| Næromsorg AS | Kristiansand S | 2016 |
| Nærøysund Tannhelse AS | Kolvereid | 2013 |
| Næss HMS | Rådal | 2014 |
| Næss-Andresen AS | Billingstad | 2019 |
| Nøste Legekontor AS | Lier | 2006 |
| Nøstetangen Fysikalske Institutt AS | Hokksund | 2013 |
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| Nøstret Kroksund AS | Krokkleiva | 2008 |
| Nøtterøy Fysioterapi AS | Nøtterøy | 2019 |
| Nøtterøy Legesenter AS | Nøtterøy | 2014 |
| Nøtterøy Tannhelse AS | Vestskogen | 2007 |
| Nøtterøy Ultralydinstitutt Ans | Nøtterøy | 2000 |
| Nøtterøyklinikken AS | Nøtterøy | 2025 |
| O&B Invest Sør AS | Kristiansand S | 2023 |
| O. a. Hauge Holding AS | Volda | 2022 |
| O2 Holding AS | Lørenskog | 2016 |
| O2 Klinikken Helgeland AS | Austbø | 2024 |
| O2 Klinikken Mo AS | Storforsheia | 2024 |
| Oa Klinikken AS | Ytre Enebakk | 2017 |
| Oag Fysioterapi AS | Vågå | 2024 |
| Oah Barne- Og Familie Støtte AS | Steinkjer | 2023 |
| Oasen Fysioterapi Da | Fyllingsdalen | 2018 |
| Oasen Legesenter Da | Fyllingsdalen | 2015 |
| Oasen Tannklinikk AS | Fredrikstad | 2018 |
| Oasen Tannlege-Senter AS | Fyllingsdalen | 2011 |
| Oasis AS | Gjerdrum | 2023 |
| Oask Legetjenester Limited Nuf | Skien | 2025 |
| Obgy Health & Care S.R.O. Nuf | Zilina | 2017 |
| Obsify AS | Stavanger | 2026 |
| Oc Tannklinikker AS | Oslo | 2023 |
| Oc Tannklinikker Holding AS | Oslo | 2019 |
| Ocean-Safetec AS | Tjelta | 2020 |
| Ocularius AS | Oslo | 2025 |
| Oculi AS | Mo I Rana | 2002 |
| Oculomotorius AS | Bergen | 2009 |
| Oculus AS | Ålesund | 1996 |
| Ocumed AS | Sandefjord | 2019 |
| Odal Fysioterapi Da | Skarnes | 2023 |
| Odd Bjørnsgaard-Andersen AS | Farsund | 1986 |
| Odd Sture AS | Tønsberg | 2003 |
| Odd T. Nesse AS | Straume | 2024 |
| Odda Tannlegesenter AS | Odda | 2018 |
| Oddaprodukt AS | Odda | 1975 |
| Oddvar Ekeberg AS | Rakkestad | 2015 |
| Odent AS | Lunner | 2017 |
| Odenta AS | Kjeller | 2025 |
| Odessa AS | Snarøya | 2012 |
| Odon Holding AS | Kristiansund N | 2022 |
| Odontia 11 AS | Tromsø | 2018 |
| Odontia 2 AS | Lillehammer | 2016 |
| Odontia 3 AS | Askim | 2018 |
| Odontia Gruppen AS | Oslo | 2016 |
| Odontia Klinikkdrift AS | Oslo | 2016 |
| Odontoblast AS | Jakobsli | 2026 |
| Odontoclinica AS | Lysaker | 2018 |
| Odyssey Coaching Systems AS | Tromsdalen | 2023 |
| Oe Kiropraktikk AS | Fredrikstad | 2022 |
| Offshore Health Services AS | Kristiansund N | 2009 |
| Offshorelegen AS | Trondheim | 2023 |