Lateral-torsional buckling behavior of various types of steel trusses without and with intermediate lateral rigid supports is investigated by performing finite element analysis. Commonly used parallel chord trusses, such as Pratt, Howe, Warren (with verticals), K and Diamond trusses of span 8 m and rise 0.8 m are considered. Two different types of intermediate lateral rigid support systems are considered. Elastic critical buckling joint loads of the trusses are found by modeling and performing finite element analysis using ANSYS - commercial software. From the obtained results it can be understood that critical buckling load, the magnitude and shape out of plane deflection depends upon whether the intermediate lateral support is provided or not and if provided, the type of lateral supports and spacing between them. The pattern and inclination of the web lacing also affect the stability of the truss. It is found that the Diamond and K trusses resulted in better stability and hence suggested for use in place of large spans and heavy loading.