In this paper, we apply new results on variational relation problems obtained by D. T. Luc (J Optim Theory Appl 138:65-76, 2008) to generalized quasi-equilibrium problems. Some sufficient conditions on the existence of its solutions of generalized quasiequilibrium problems are shown. As special cases, we obtain several results on the existence of solutions of generalized Pareto and weak quasi-equilibrium problems concerning C-pseudomonotone multivalued mappings. We deduce also some results on the existence of solutions to generalized vector Pareto and weakly quasivariational inequality and vector Pareto quasi-optimization problems with multivalued mappings.Keywords Generalized quasi-equilibrium problems · Upper and lower quasivariational inclusions · Quasi-optimization problems · Upper and lower C-quasiconvex · Upper and lower-quasiconvex-like multivalued mappings · Upper and lower C-continuous multivalued mappings · C-pseudomonotone · C-strong pseudomonotone multivalued mappings Mathematics Subject Classification (2000) 49J27 · 49J53 · 91B50 · 90C48