Numerous neurological diseases lead to paralysis of intact skeletal muscles. Electrical stimulation of these to restore contraction is problematic due to side effects, the lack of cellspecificity and simultaneous activation of antagonist muscles.Optogenetic stimulation of skeletal muscles expressing the light-sensitive cation channel Channelrhodopsin2 (ChR2) could overcome these limitations. Therefore we have generated a transgenic mouse line with expression of ChR2 fused to EYFP in skeletal muscles under the control of the chicken-β-actin promotor. Soleus muscles showed membrane bound EYFP fluorescence and light induced force was analyzed by isometric force measurements upon illumination (470nm) with different durations, intensities and repetition rates. Using single light pulses, the highest force generation (52.7±3.4mN, sd, n=4) was reached by 100ms long pulses with a light intensity of 0.51mW/mm2. For tetanus stimulation we found that 5ms pulses at 30Hz and 1.4mW/mm2 were most efficient and led to the force of 69.1±7.7mN (sd,n=4). This was ∼70% of the force generated by electrical tetanus stimulation.Bilateral laryngeal paralysis is a severe disease resulting in immobility of the vocal cords and life-threatening dyspnea. In this disease electrical stimulation is problematic due to electrode corrosion, recognition of the stimuli and non-selective stimulation of agonist and antagonist muscles (Zealer DL et al., Laryngoscope 2003,113:1149-1156). We therefore tested the feasibility of selective optogenetic stimulation of the posterior cricoarytenoid muscle, which is the only intralaryngeal muscle opening the vocal cords. Larynges were isolated from ChR2-transgenic mice and locally stimulated with a light guide (O400μm,NA=0,48) in the postarytenoid region. Application of light pulses (470nm,50ms,35.7mW/mm2) led to a repetitive opening of the vocal cords. The distance between vocal cords during illumination was 230±38% of baseline (sd,n=3).Thus optogenetic muscle stimulation is a promising method for therapy of nerve lesions and might be useful to treat bilaryngeal paralysis.