The continuous decline of biodiversity and the acute problem of climate change had led to an increasing interest in ex situ long-term conservation. The Checklist and Red List of Romanian bryophytes includes 979 species, of which 374 species (38 %) are considered threatened but only 10 species (2.67 %) are protected by legislation. We have started at the Institute of Biology, Bucharest a bryophyte in vitro collection for conservation, fundamental research and biotechnological purposes. The initial objective was to develop standardized and efficient protocols for collecting, micropropagation and storage of bryophyte species for short, medium, and long term periods. Bryophyte samples were collected mostly from protected areas, with little human impact. As a working principle, the lab methodologies were tested initially on common species. This preliminary approach avoided a negative impact on the threatened populations and allowed numerous and repetitive tests regarding their in vitro behavior and culturing requirements. Establishing in vitro systems in bryophytes was significantly different compared to those for seed plants: (i) the sterilization protocol has to be more gentle, (ii) only minimal nutritive composition (without carbohydrate sources) is satisfactory for growing and multiplying, as Knop formula (1865), (iii) the requirements for temperature is much lower (10- 20oC), (iv) and the passages are more frequent, for avoiding the uncontrollable proliferation of endophytes. A problem in in vitro plant collections is their persistence for medium and long term, without contamination and/or spontaneous genetic alteration (somaclonal variations) and with low costs. We developed a method of medium term conservation of bryophytes by growing cell cultures at low temperatures (10oC) and low illumination (1500 lux) on minimal nutritive medium (Knop, 1865). In such conditions, nutritious fresh media transfers were made at 3-6 months. The ongoing researches focus on the cryopreservation of bryophyte germplasm. Cryopreservation has obvious advantages over in vitro storage in terms of space saving, improved phytosanitation and diminished genetic instability. The suitability of bryophytes for cryopreservation is sustained by their capacity for revival from anabiosis, and their constitutive extreme tolerance to desiccation. We tested and validated micro-multiplication protocols during 2005-2010 for many species of bryophytes that were maintained in in vitro culture for variable periods of time (Cogălniceanu et al., 2006, Cogălniceanu & Stoiculescu, 2007): Asterella gracilis (F.Weber) Underw., Athalamia hyalina (Sommert.) Hatt,, Bazzania tricrenata (Wahlenb.) Lindb., Calliergonella cuspidata (Hedw.) Loeske, Cratoneurum sp., Dicranum sp., Funaria hygrometrica Hedw., Hylocomium sp., Leucodon sciuroides (Hedw.) Schwägr., Mnium sp., Philonotis sp., Plagiomnium sp., Polytrichum longisetum Brid., Porella platyphylla (L.) Pfeiff., Pottia sp., Preissia qudrata (Scop.) Nees, Reboulia hemisphaerica (L.) Raddi, Sauteria alpine (Nees) Nees, Thamnobryum sp., Tortula muralis Hedw. Our in vitro bryophyte collection holds presently a number of six species, belonging to both liverworts and mosses.