Is there an option, like on lights sources, to tell the object that has an emission shader to not cast shadows in the scene?

• Lights sources have a no shadow checkbox - yay! Thanks for including those four extra words in your question. – uhoh May 26 '16 at 8:44

Simply go to the object panel on the right, scroll down to the Ray Visibility panel, and uncheck "Shadow". Note that this will apply to the entire object, not just the material.

• This checkbox applies for the mesh that should not cast ANY shadow. I am not sure but this might not even work when the emissive entity is not marked to with "Multiple Importance Sampling". A mesh as light source does not trivially behave the same way, as a light in any raytracer. In case GabrielS wants only one light not to cast shadows and for all objects, this will not work. – Róbert László Páli Aug 28 '13 at 16:40
• How does this have so many upvotes? This turns off shadows that this object is casting, does not influence shadows cast by the emission light source. – Jaroslav Jerryno Novotny Mar 21 '18 at 19:14

I have the following nodes:
Geometry, Emission, Transparent BSDF, Mix Shader, and Material Output.

The Geometry node makes the emitter one sided by connecting "Backface to Mix Shader/ Fac" (the grey input).

Transparent and Emissions also input the the Mix Shader/ (shader inputs the green ones)

Then the shader connects to the Material output.

• This does not answer the question. Your shader is just turning off the emission for the backfaces, not removing the shadow. – David Feb 3 '15 at 15:15
• This almost nailed it, but you shouldn't use the Mix Shader, but the Add Shader instead (see my answer), and the Geometry node isn't needed. – Watcom Mar 13 '15 at 4:32