Experimental results on laminar propane flames propagating in a narrow gap between parallel glass plates are presented. Development and evolution of cellular flame structure is demonstrated by video and long-exposure photo recordings for stoichiometric and fuel-rich mixtures with equivalence ratio of 1.0:1.25. It is shown that in narrow gaps the lateral cell sizes by far exceed the gap width. Average flame propagation speed obtained for gap widths between 2.5 and 4.4 mm is shown to depend significantly on the gap width due to the effect of heat losses on the normal flame speed, as well as due to cooling of products behind the flame. Effect of gap width on the cellular structure is demonstrated, and statistical characteristics of the cells are obtained for two gap widths. Flame propagation patterns are also obtained for non-central ignition performed at one or simultaneously at two points.