Juvenile wood characteristics of multiseriate and uniseriate rays of five species of the genus Acer were studied on young trees from France and Canada. Ray height, width, number in width of cells and proportion/mm2 were determined for the earlywood. Variance analysis was used to discriminate the variability of the characteristics of rays. Simple regression analysis shows some strong correlations between the characteristics of multiseriate and uniseriate rays of each species. Except for A. saccharinum, no relationships were established between the ray characteristics and the specific gravity. Except for A. pseudoplatanus, no relationships were established between annual ring width and ray characteristics. Principal component analysis focused separatelyon multiseriate rays and on uniseriate rays revealed differences between A. saccharum and A. saccharinum (e.g., the proportion and the number of cells in multiseriate rays).