Objective: Nasodren nasal spray (Cyclamen europaeum extract), is used in some countries as an alternative therapeutic agent for sinusitis. The aim of this study was to ivestigate the possible cytotoxic effects of the drug on cell morphology and viability in L929 mouse fibroblast cell culture model. Material and Methods: Nasodren solution was diluted to the dilutions of 1:25, 1:50, 1:100, 1:200, and 1:400 (w/v), and these dilutions were grouped from I to V, respectively. The control group was prepared by using saline in a 1:1 ratio. L929 fibroblastic cell culture material was incubated in 96-cell incubation medium. Following a 12-hour incubation period, the material was taken into fresh culture medium and was stored for five days after treatment with various dilutions of the test material. Cell morphology was observed under microscope on 1(st), 2(nd), 3(rd), 4(th), and 5(th) days. Cell viability was evaluated by 3-(4.5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide colorimetric assay method on the same days. Results: Cells maintained normal fibroblastic shape and morphology in Group V and the control group during the incubation period. Normal round ring shape was apparently lost in Groups I-TV. Cell viability decreased in Groups I-TV, whereas cell viability increased in Group V and the control group. Conclusion: Results of this study indicate that higher concentrations of Cyclamen europaeum have toxic effects on cell viability in vitro. There is need for in vivo animal studies before safely prescribing this drug as the first line treatment of sinusitis.